"I can't recall off-hand anyone here or elsewhere objecting to using nuclear bombs to deflect asteroids. Even the most rabid environmentalist can do a risk analysis on that one."

In another forum (Centauri Dreams) just recently physicist & SF writer Greg Benford was attacked by a rabit anti-nuke for simply considering the option. You made a falsifyable statement about human nature. Rabid ideologs are NOT amenible to facts or arguements based on reason q.v. folks willing to blow up themselves and their children. In addition the extremist branch of environmentalism takes the position that this planet would be better off sans humans. What more 'natural' method than another NEO 'drive by'?