Bombing from orbit doesn't require that much in the way of weaponry. Recall the movies "Deep Impact" and "Armageddon" and their "chunk of rock from space being exponentially worse than nukes" scenarios. That is the principle behind kinetic energy weapons. You just toss a piece of sufficiently massive matter out the door and if you aim right, you get the same effect as a nuclear weapon. This is not something I made up - it is a common idea in science fiction, called "kinetic energy weapons." And hostages? Really? You think the big profit-hungry corporation is going to let THAT stop them? A KEW strike wouldn't leave enough bits for forensics to contest their assertion that the natives whacked the hostages anyway. And anyway, I am pretty sure it means good guys. The camera showed the fat black guy and the scrawny nerd when it said that, and it showed the corporate boss guy being led off in the line of those being kicked out. So, not hostages.

One few final notes
- The "ridiculously exposed rotors" are less exposed than helicopter rotors which have been used in combat against foes far more technically advanced than the Pandorans for over fifty years.

- Your counter-argument against humans being the underdogs seems to be that humans are just so badass that severe numerical, environmental and physiological handicaps are insufficient to overcome their awesome toughness!

- Your arguments about the capabilities of the corporation to come back again are a little strange. You talk about the prohibitive expense of sending the expedition as if it could be reasonably expected to bankrupt the company, but at the same time seem to think that space travel is so common as to enable companies to blithely send out mining expeditions on other planets without government approval and open assistance! Any company with the wealth to invest in interplanetary mining ventures, genetically engineer avatars & patronize useless scientists on the off-chance they might come up with something interesting, is going to have significant investments in government. If they really are operating on a shoestring, with all of these prohinitively expensive investments being underfinanced gambles hoping for a big return to pay for them, then there must be other, more wealthy and powerful companies capable of learning from the mistakes and going in full bore. If the company is the most wealthy and dominant company in the world, this loss could not have undone them - they have the ability to make so much more money from the technology they demonstrate that this one expedition cannot possibly be their sole or primary hope of income.
- If they can engineer Pandoran life-forms so as to create avatars capable of interacting biologically with the natural ones, how long do you think it would take them to whip up so bioweapons capable of taking care of all those naked savages without risking a single infantryman?