If Cameron is going to call out the US military in such obvious terms, it would be nice if he did the same with the Navi. How about if their leader was a monster who kept the female of their species in complete subjugation, with an occasional stoning, kept from all spiritual enlightenment, and perhaps a mass grave or six? Then our moral universe would at least be fair. It's insulting the way he takes pot shots. If you need a black-and-white universe for your little science fiction film, there's plenty of means of doing so without preaching your infantile world view to people are just looking for a bit of entertainment.