Well, I think he meant that the main purpose wasn't to stop Global Warming, but rather to inform people of its possible effects. If this movie was based on an essentric climateologist that wanted people to stop pollution and everything that affected global warming, he would have left the movie. Rather, they talked about the subject, but kept it objective and informative, rather than "liberalish", for lack of better words.

Well, thats what I took from his comment, anyway.