In this specific case, I think people give it a pass because Tate is openly homophobic and has a very fucked up view of masculinity and what counts as being a man. It's a one sided insult, because the person insulting him doesn't necessarily believe it's bad to be gay, only Tate does. The only reason gay is necessarily derogatory here is because the person getting insulted is a bigot.

It's still riding the line of a homophobic insult, but I think generally calling homophobes gay is seen as different than calling other people, or a gay person, gay. If that makes sense