First off, you replying to a liberal poster so if your goal is to encourage the conservatives on the site to be less troll like you're aiming in the wrong direction... wasted fire anyway, there are proportionally very few conservative threads on the board. You are mostly informing a group of primarily socially moderate conservatives that people don't like angry social conservatives. This is also where liberal media bias factors in, it's hard not to be perceived as radical when you can take as a given every bad remark will get 5 times as much negative coverage as the other side's slips.

Your core point really is quite correct. Whatever I or others might think of moderates, their views decide pretty much every election, and perception of fanaticism, regardless of its validity, turns voters in the middle off big time.

However, and this is a big point, during the primary of a race to challenge an incumbent the non-incumbent side always seems far right/left compared to the incumbent, because they must solidify their base while the other guy must do only enough to appease his while playing to the middle. The latter is much easier than the former. This would be a big concern, and is a legitimate one, but the reality is that the primary is usually over between February and April, as will be the case this time too in all likelihood, and people will have over half a year to forget such things while the challenger hits the incumbent. And considering the nominee will almost certainly be Romney, who even the Dems have been calling moderate and who is burnt into most of the population's head as moderate, I really doubt come election day very many people will be thinking 'Hmm... can I risk voting for Romney? He's such a radical.' and unless he picks someone with low charisma or noted for their social crusading, which is unlikely, very few people will fear the ticket. Especially after months of being bombarded in the swing states with positive ads about him. They can hit him negatively about his business or economic practices, but those aren't 'scary' to most people, and they can try to hang the more scary conservatives around his neck, but if this combative primary has served no other good purpose for the party it has definitely locked into a large portion of the populace's minds the idea that Romney doesn't get along with those sorts and is unlikely to be very influenced by them. So while doubtless some people will vote for Obama on the grounds you suggest, I don't think it will be all that huge a factor.