Is this supposed to be a clever retort?
I'm all for politically incorrect humor. Matter of fact, I love that kind of humor. But a man joking about having sex with another guy is not politically incorrect. It's homosexual. So homos will find this humor funny. Not that there's anything wrong with being a gay. Just not my thing.
EDIT: I'll be clear though, there's nothing wrong with him saying what he said. I just don't find it funny. Never got into Will & Grace. I'm more of a Family Guy type of humor.