When you get down to it, no art has any greater reason to exist. Feel free to criticize the organizers and their motives, but they were still well within their rights.Criticizing art, and the reason certain art exists, is not equivalent to "she wouldn't have been raped if she didn't dress like that." It's a super, horribly gross sentiment.
Regardless, you shouldn't try to make your point by sweeping generalizations about how GAF members feel about rape victims.