Just because you are gay does not mean you are not homophobic.

They likely meant that it’s a joke about power dynamics implying sexual preference. That is homophobic, but funny, but also homophobic.

In short, just cause you like it up your arse doesn’t mean you are a spineless idiot with no power. Instead Let people enjoy things and try to stop the spread of these stereotypes even in jokes. You never know who hears them and what social climate you might propagate into the heads of others and youth. If you are aware of these caveats you are allowed to make the most offensive jokes.