It is victim blaming, we are not the reason homophobia exists or that people become extremely homophobic. It is not oppressed people that cause their own oppression, we don’t in some way “deserve” it.
Some aspects of the identity of sexuality may be related to physical and things we cannot control, but at the end of the day it is an identity. If they do not see themselves as gay, they are not. It is not for you to assign an identity to someone, even someone you don’t like. Even if someone might identify as gay outside of these power structures, in here they aren’t. Even if they would be gay, they participate in our oppression because being straight is beneficial to them, not because they “are secretly gay”. If they did homophobia because they were “ashamed” it wouldn’t be helping so many of them get into positions of power
There is a correlation, though. I for one was deeply homophobic before I came out of the closet, and it was based on my fear of being labeled gay.
My friend’s homophobic dad was diagnosed with HIV right before his wife filed for divorce. They had a long discussion about how he got it, and he admitted to it being another guy. She was very lucky not to have HIV as well.
There does exist a correlation, but like all generalizations, it does not apply to all cases and can come off dismissive, rude, or minimizing when it isn’t actually true. I find that it’s best to avoid sweeping generalizations for people at all.