Honestly this sounds like some kind of PTSD response. This kind of irrational turn, especially after witnessing first-hand what homophobia leads to, doesn't make a ton of sense otherwise.
Doesn't absolve them, since they're promoting hate and is a complete betrayal of those who were killed, but I wouldn't be surprised if this were some kind of semi-conscious attempt at self-preservation.
Recently found out about https://elan.school/ which ended up being run by ex "students." It's not the same thing, but there are parallels. Conversion therapy is essentially brainwashing at it's core, and I find it fascinating (in a horrifying, train crash, can't look away, kind of way) that in both cases, ex members become involved in perpetuating the horror.
I'm on chapter 71 right now. Just an amazing story. My heart goes out to all the former Elan kids, and there are plenty of abusive places like Elan operating today. And many kids are sent to them to get the queer forced out of them, even if the school doesn't officially practice any form of so-called "conversion therapy."