Seems reasonable to me that it's a network effect. Hating gay people is a thing their community does, so they do it to fit in with the community, at first, and then it becomes part of who they are after they've done it for a while. Their "culture" in a sense. But if their community sees them as gay, or gay enough, they'll be targeted by their own discrimination and lose their community and be outside the pack, which is what they actually fear. And if one of their friends starts getting too close to gay, they may have to hate them and cut them loose just to make sure the target doesn't spread by association and cause people to start hating both of them.

As acceptance of gay stuff increases, they see their community shrinking. Their "culture" has fewer and fewer people, which means their pack is getting smaller, and all they want with all their hearts is to be firmly in the biggest safest strongest group. So their group gets smaller, but can they change? Can they just give up hating at this age? Can they honestly see themselves forming community with those people? They still have some people in their community, the ones closest to them, that they'd still have to give up if they changed. Maybe their uncle and brother and mom, people important to them, and so as uncomfortable it is to be on a shrinking island, they'd rather that than to be alone with no one they knew. So they keep fighting, but with a new discomfort, the knowledge that they're fighting for a losing side.

This makes them all the more dangerous, as they're more willing to do anything to overcome their worsening odds...