Politely disagree. Saying something (even generalizing, which always tends to be wrong somewhere) about homophobic people doesn't say anything about non homophobic people. You don't have to identify with every gay person on earth, and you shouldn't. There are gay people who just so happen to be assholes, too. Their existence doesn't say anything about you at all.

It is victim blaming

I don't think so personally. They are still the oppressor in the situation. "Being secretly gay" is an attempt to explain, not to shift blame to you.

we are not the reason homophobia exists or that people become extremely homophobic

I think it's useful to seperate a causal explanation and the idea of responsibility. The fact that people are individuals and not unanimous blobs is - purely causally speaking - the reason why animosities based on our differences exists. Does that mean that the victims of hate are to blame? Definitely not. It's always, always the responsibility of the one who commits discrimination.

It is not oppressed people that cause their own oppression

I agree, but more precisely it is homophobic people, gay or not, who cause the oppression of non homophobic gay people. I think this is true independently if the stereotype is true.

we don’t in some way “deserve” it.

Absolutely agree. Nobody deserves that.

If they do not see themselves as gay, they are not.

The idea is that they kinda see themselves as gay, or are afraid they might be, or subconsciously know they are; and because of extreme toxic masculinity and sexism they get hateful and aggressive.

There surely are non gay homophobic people as well though. After all, some hetero people happen to be assholes as well.