I think your interpretation of the blocking of that scenario is a valid alternative, except in the context of the show, that was not the way it felt. Carl had been itching for a chance to flex his muscles, figuratively speaking, and was making excuse to justify his exercise of that power. He shot the kid because he could. There was no need for a Mexican standoff mindset which might have justified the zero-tolerance, as Herschel also had a gun on the kid and was backing Carl up. I think the point was that the Woodbury guy was just a scared kid, rather than any sort of hardened veteran. The point was made at earlier points in this season that the Grimes gang are a lot tougher and more seasoned than most of Woodbury, which consists entirely of soft civilians, excepting some of the Governor's best thugs. The navel-gazers who wasted weeks of our lives on Herschel's farm died in the off-season, and by the Season 3 premier, even the young girl, the old man and the pregnant lady were efficient killing machines. The weakest resident of the prison is named "Lil' Asskicker" for crap's sake! I would be hard-pressed to identify a member of Rick's group, aside from the baby, or someone carrying it, who would be capable of losing a fight to Milton or Karen, who are implied to be typical of the Woodbury group. That's also why they were okay with taking so many of the Woodbury residents in at the end - without the Governor and Martinez, they are no threat, and the core prison group's new role is to be protectors. We might see one or two Woodbury types with speaking roles next year, but I think they are going to be extras for the most part, with maybe Karen or someone like her speaking for their concerns, and Tyrese and maybe his daughter, becoming integrated into the original group.

Regarding Carl, the thing to remember, that a lot of people I have seen discussing the show on a TV review site seem to have missed, is that this is not an ensemble show like Lost. This is entirely a show about Rick. The other characters are people in Rick's life, of varying importance, but not the focus of the story. This is Rick's character journey, and by extension it is Carl's as well. My general rule of thumb about the children of important male characters is that daughters are vulnerabilities, and sons are extensions of the character. That is why the couple had a girl in "Knocked Up" and why the "Three Men" had a female "Baby", that is why ever other movie or show of that genre (male lead unexpectedly has to deal with a father role) features a female child, and why Arnold Schwarzenegger only had daughters (with one exception, which I will get to in a bit). When the show or film is about the hero trying to support or protect or save something, a daughter is someone vulnerable and weak. Her role goes beyond the task we see the hero trying to accomplish, because he has to protect her for her entire life until a worthy suitor relives him of that burden.

A son, on the other hand, is a continuation of the father, and why a dead father's woman will give birth to a boy 9 times out of 10 (exception being if he already has worthy sons). That is why in the one Schwarzenegger film that comes to mind where he has a son, "Jingle All the Way" he is fixated on finding a particular toy for the kid. Sons are there to be satiated, because it makes the hero's action noble, instead of selfishly satisfying his own desires. Likewise, sons represent a sort of immortality for dead fathers, which is why men with sons tend to get killed in action movies. The army guy from the Transformers movies would never have survived the first film if that baby he was Skypeing had been a boy. But that little girl needs a daddy to provide for and protect her, so Ironhide drives him home in the closing montage. Otherwise, it would have been Optimus Prime and Jon Voight presenting the little boy & his mommy with a folded-up flag.

The point? That is how we have to look at Carl. His role as a character is to stand in for Rick on development. You can't spend season after season with Rick bouncing between extremes trying to get a handle on the zombie apocalypse. If at a certain point characters don't figure it out, the audience is going to lose patience with them. And we came damn close midway through season 2, as multiple characters who weren't Daryl failed in that respect, or else overreacted with suicidal tendencies.

In Season 1, Rick was still hopeful of finding a way out or through this disaster and back to normal. He woke up in the middle of it, it didn't happen to him like it did the others, who at least at an adjustment period, so he was first having to come to terms with the scope of the disaster, and that was how the first season ended, with the realization of what kind of world they had to deal with now, and the impossibility of getting the old world back. These next two seasons have been about finding the right balance to live in the new world. In Season 2, they were mostly in denial about the severity of the apocalypse. They hung out on an idyllic farm, trying to live like they always had, pondering the pros and cons of pregnancy and making the tests a priority on a salvage run, and cleaning wells and arguing about who has to sleep in the camper or the farmhouse or who has to do chores and trying to keep zombies alive to be cured and other stupid things that frustrated the piss out of us, because our brains had moved on well past the characters themselves. We were already in the "brave new world" mindset, and this dithering over pointless issues and low-priority tasks was infuriating when we all knew the zombies would inevitably ruin it. Season Two was all about teaching the characters that not only was the old world gone, but so was the old way of life. Day to day survival in the old (and real) world is pretty much a given. If something in the real world is going to kill you tomorrow, there is nothing the average person can do about it. On the other hand, in a zombie apocalypse, you WILL die tomorrow, or even today, unless you take precautions. The zombie herd that overran the farm and killed the sort of people who forget to lock their doors while driving through a swarm of undead was the irrefutable lesson to Rick and company, and was subsequently reinforced by hard days on the road that reduced them to the point where they were willing to entertain the notion of eating cat food.

When this season rolled around, they had finally got to the place where survival is no longer taken for granted, has become an urgent priority and has overwhelmed the niceties that were so important to them in the previous seasons, when they bitched about washing clothes and respecting each others' feelings when criticizing their shooting. The struggle in this season has been to relearn humanity. Human beings have survived, thrived and built highly functional societies in more hostile and dangerous conditions with fewer advantages than Rick's group had. They can keep going on like the feral survivors who didn't speak a word in the opening scene of the season premier until after the credits had rolled, but they wouldn't have lasted much longer. At some point, they need to settle down again and start building something. This season is all about learning how to do that.

For those people who flunked out of Drama 101, it may come as a shock to learn that "The Walking Dead" has a second meaning. Beyond the zombies, it refers to the human survivors themselves, who are pretty much doomed eventually. Their only hope is to rebuild a society, or all end up like that hitchhiker whose backpack they looted on the roadtrip to Rick's hometown.

It is to that end that the Governor served as a villain. The Governor was not a threat to Rick's life. The fight between the prison group and Woodbury was never shown to be entirely one-sided, but rather an up-in-the-air match-up of the skills and defensive position of the group, versus the numbers and resources of Woodbury. The physical danger of the Governor was not that he'd win a war, but that in the fighting of that war, and we might lose someone we had come to care about or respect, now that the deadwood had been shed at the quarry, the farm, the CDC, on the road, taking the prison, and in childbirth.

The Governor was also never a viable alternative to the Ricktatorship, whatever the weenies at Hitfix.com might have liked to think. Yes, he had a seemingly nice, normal town that had a decent population and was safe and happy, but it was rotten through and through, which is why Michonne wanted out practically as soon as she had a look around.

The Governor vetted newcomers based on utility, for example, only taking an interest in Tyrese when they were found to have knowledge of the prison. He was not willing to live and let live, sending Merle after a lone woman who declined to stay in Woodbury. He was not interested in competent people who might be a threat to his position and power, as seen with his murder of the soldiers. When a crisis struck Woodbury, he was nowhere to be found in the aftermath of Rick's raid, failing to provide leadership. He gave the people bloodsports to amuse them, rather than setting a better example of ways to pass the time or hone skills. He did not train people to protect themselves, but kept them reliant on his clique of fighters. All the ways in which he was similar to Rick that came up during their sitdown, were not to humanize him or show depth, they were to point out that he is BAD, that he is WRONG, because of those very similarities to Rick, who did NOT go bad, despite his own sufferings and losses. The Governor was also contrasted against Michonne, who like him, kept pet zombies - but only for their utility, and she ditched them as soon as they were no longer convenient. The Governor's willingness to kill over his zombie daughter shows that he values his own selfish wants over other people. He picked the dead over the living. It cannot be any more clear than that.

Finally, the Governor slaughtered his people as the ultimate failure of leadership, proving that they were never anything for him but a means to an end. When they failed to kill the people he wanted dead for his own emotional purposes, he discarded his followers like useless tools. There is very little difference between the Governor and a zombie in the grand scheme of things. They both move around, mindlessly seeking satiation through consumption, and all they represent to living people is a lethal threat. Aside from trivial medical details, there is no essential difference. All the virtues or attributes of human beings that elevate them above zombies or animals are absent in any significant degree in the Governor (and largely in Shane, too).

The Governor's purpose this season was the be the Anti-Rick, the Rick who could have been, if he had gone crazy or evil. The threat was not if the Governor could wipe them out, or at least no more so than any one little slip in almost any scenario had that potential, but rather, that he was willing to do so without any genuine grievance, and that he manifested the last temptation of Rick, with his offer of peace for Michonne.

The show was not about weighing the greater good against a single individual and blah blah blah, which they showed by having him, in the same episode, before Rick had even considered the offer seriously, tell his subordinates to murder Rick & company when they turned her over. That was never a choice, it was only presented by the show as a potential mistake. Rick presented the choice to Herschel as a choice between Michonne or their children, but that is merely one degree removed from the "every man for himself" mentality that makes you just a less-visually-revolting walker.

Morally and tactically, even without the Governor's intended immediate treachery, it was wrong as well, and it was the realization of his error in that regard that made Rick resign as Ricktator.

So the point of the season has been about Rick moving away from the Governor's path. He has had to learn to accept others into the group, like Michonne, lest he eventually go the way of Morgan, and it was Carl who told him as much, as a throwback to Rick's better nature. He learned to move away from the Ricktatorship (personal sidebar: I'm going to miss that term), which left the group paralyzed without his leadership during the Governor's first attack on the prison.

His welcoming of the Woodbury refugees is the proof that this is a real change, not just an intention that might falter when the next applicant to join the prison gang looks a little shady or creepy. Rick (and by extension, the group) has learned to look beyond the immediate practical considerations, that led him to trade Michonne and abandon the hitchhiker. It was basically his "Grapes of Wrath" and the Woodbury group is the sick guy in the barn and the prison is Roseasharn's boob he is finally permitting strangers to suckle at.

And from there we come around to Carl. Rick learned to accept the apocalypse in season 1, he learned that he had to toughen up and learn to survive in season 2 and he learned that he needed to be worthy of survival in season 3. He has learned to be hard, but not too hard. Further lessons would be redundant, so Rick is pretty much dead as a dynamic character (there's a reason Steinbeck ended GoW when he did), unless he is going to continually devolve and need to relearn lessons all over again. In lieu of that, the writers have set up the next best thing: Carl. Carl is the extension of Rick. Beyond his own day-to-day survival, the most important thing for a man with a son, is the raising of that son, teaching him, and setting a good example. The son is the extension of the father, after all, whose survival will be Rick's immortality. If Rick spent three seasons learning to get it right and hit the right balance to be a benevolent barbarian warlord in a lawless time and place, but raises his son to be Governor Jr, why did he bother killing Shane? Shane could have done the exact same thing for Carl.

Carl's little episode in the finale (complete with a pragmatic rationale of the sort Rick has just learned to move beyond) was this season's equivalent of that glimpse of the prison in the distance last year - foreshadowing of the stuff to come next year. In this case, Rick's new character arc will be setting Carl straight. Shane in season 2 was annoying because we all just wanted Rick to shoot him already, and we knew he'd try to kill Rick eventually. Every moment that Shane lived was a moment of Rick being an idiot. On the other hand, a Carl acting like Shane will be far more interesting, since even if we might want Rick to kill him, we can't ever expect that he would, and his betrayal of Rick would not necessarily be inevitable. Carl is being set up as the ultimate loose cannon, that in this world where each man is his own ultimate authority, Rick cannot deal with as he would Merle or Shane or another recalcitrant group member.

In the end, what I am trying to say, is that it is all of a piece. The Walking Dead has definite ideas about right or wrong, and is not about a bunch of gray areas or equally valid alternatives which are justified by survival. By the moral rules the show has established, what Carl did was wrong, and he and Rick passed each other going in opposite directions. Now Rick has to overcome the bad lessons he has taught Carl with his mistakes this season. Earlier, Carl had it right, when he took in Tyrese & co, but took precautions to protect his own people, when he urged Rick to consider Michonne as one of the group, and even when he went after the family picture in their hometown. His contemplation of that same picture in the finale is intended to be a direct contrast to his welcoming attitude in that episode, and his new eagerness to wield his power and smite their foes, which he sees as justified by the same practical considerations Rick now regrets letting him be deceived into surrendering Michonne.

Long story short - Carl done go bad, and it's Rick's fault and his major character issue for next year.