First amendment. Free speech. Say what you want. I won't send a ban hammer at anyone using the phrase.
Though on a personal level, I find the term repugnant and anyone who uses it to be a piece of shit. Just cause you can say something doesn't mean you should.
Well, we're not necessarily talking about the law here, I don't think it should be illegal to say it either, however in terms of this site I believe that a certain amount of effort should be taken to make sure that this is a welcoming place for people with special needs.