I'm not in favor of this mosque.
Just because you have a right to do something, doing it doesn't make it right (or whoever the saying goes).
If the builders are to be believed, the center's supposed to be a building that promotes tolerance or whatever, with a mosque built in.
If they really want to promote islam as a religion of peace and tolerance, or whatever the fuck their message is, why don't they throw that money into rebuilding the wtc? They can say something like "this isn't an admission of guilt of blowing the towers up, it's just a sign of compassion for the wrong that's been done here". That would really slap the shit out of everyone who's an islamophobe. Of course, these assholes would never do it.