No offense, but...*yawn*
Disney has in its own vault fantastic creatures and vistas that have yet to be translated into a ride or attraction. The most obvious example is Fantasia. I don't go to a Disney park to see rides based on other people's visions. I remain respectful but unimpressed by James Cameron. I go to a Disney park to see DISNEY product. I would take an original, Disney-generated attraction, based either on a prior Disney feature (such as the aforementioned Fantasia) or something brand-new (Beastly Kingdomme) than anything Cameron's cranked out any day.
You make a good point about Avatar's politics, such as they are. Its story does involve the same old anti-militaristic lecture Hollywood loves to belabor. The film does have a certain attitude. I don't think that's any kind of factor for cancelling the project, however. There are better arguments for doing that. Such as: Avatar is a flash-in-the-pan, with a poor story, dull characters, and not much chance of longevity, based as it is on eye candy. Iger's idea to buy the rights to it for WDW was a dumb, desperate attempt to trump Potter, and as such, it's pretty much failed, in my view. It's not generating the excitement the Potter attraction did prior to its opening. The movie is just a visual feast at best, and to me, that's not a good enough reason to invest in it as a Disney park attraction. After all, Captain EO was once considered cutting edge, and its star, Michael Jackson, seemed invincible. My, how times have changed...