Its not just him I've heard it from: the comparison with Dances With Wolves, the whole element of Humanity as the Bad Guys (except for those few who betray their own species to defend the Noble Savages against the evil White Man who's come to Ruin Them), this is something I've heard over and over again in reviews.
Meanwhile, its also not just the Right Wing who take issue with this movie. One prominent left-wing reviewer (unfortunately i don't have the link) that I read made a point of how this is only the latest in the "White Guilt" movies; which involve the White Man assuaging his guilt by "going native"; and are ironically inevitably racist themselves as we watch the White Man become the BEST Native Ever, much better than the actual "darkies", and inevitably he's the only one who can defeat the other Bad White Men and their stooges in order to save the day, because there's no way any of the Savages themselves could. In many of these movies, the other Noble Savages even end up making the Guilty White Man Gone Native their new chief.
Also, I'm not sure which spoiler you're referring to, but if its to do with either the Gaia consciousness being a real thing, or the human dude getting to become a Real Boy at the end, those both just make it worse. The former because it removes any question of moral doubt from the story (The Noble Savages are absolutely objectively RIGHT, which means that the humans are absolutely wrong), and the latter because its just another cheap White Guilt gimmick. If Tom Cruise got to really become Japanese at the end of the Last Samurai, or Kevin Costner got to really be an Indian at the end of Dances With Wolves, wouldn't that just make those movies even more atrocious?
I don't know; I think I'm going to see Sherlock Holmes instead...
RPGPundit