It's only anecdotal, but a lot of the people I know who were hateful like that while growing up actually did come out as LGBTQ+. Some were trans, some were gay, some were bi, etc.

Some of them are just a-holes though. One dude complained about a gay classmate. He never liked it when I asked him why he was thinking about what the other guy was doing with his bits so much. I've always thouht it was a fair question. I never did get an answer, though.