when you use gay shit as an insult, even if you "don't mean it" or justify it by saying you're only using it in THIS CASE because this one guy deserves it, you're still reinforcing the idea that gay shit is a joke, that being gay is bad, and that the worst thing you could call someone is gay. it's the same with dinguses that claim to be woke but intentionally misgender/deadname trans folks they don't like (e.g. Caitlin Jenner).
if you say something homophobic, it doesn't mean you're an irredeemable homophobe - sometimes there's layers of learned behavior and shit to unpack. but if someone calls you on it and you double down on it, maybe take some time to reevaluate your beliefs and priorities, because it sounds like at the very least you're chill with using homophobic shit to get over on someone.
I've specifically avoided chiming in or pointing shit like this out because the last time there was a goddamn meltdown, so please note that I am not claiming that this is the only homophobic shit I've seen, it's just the one where a discussion about it has gone on for pages and pages now.