Perhaps the words don’t mean what you think they mean.
This is not calling them gay as an insult. If it were saying “they are so gay” meaning “they are so bad” then yes. But this is drawing parallels between their behavior and that of gay people in an ironical way in order to highlight their hypocrisy. And frankly to taunt them.
Either you are being disingenuous or you are just not very bright. Either way, have a nice day.
I just don’t think “hurry durr they’re gay for each other” should be used as an insult, and that doing so is homophobic. Have fun on 4chan.