They could just be intolerant bigots. There are any number of reasons someone might hate someone, and the logic of "they must just be gay" doesn't really work for other types of bigotry and racism.

Deeeeep inside... Hrrngh

I don't really like this- for one, it's based in the fact that homophobic people who also engage in queer behavior in secret tend to be outrageous in their hypocrisy. Thus, because it's such juicy news people tend to assume it's more common than it actually is. This is called the availability heuristic.

For another, it individually pathologizes the condition of being homophobic as being rooted in psychological reaction formation- thereby denying that homophobia is something encultured by the broader homophobic social system that we live in. The condition of being a gay homophobe isn't a psychological one but a sociological one- it's not (just) shame but a very real fear of the very real consequences which recruit them to uphold the very system that oppresses them.

Reminds me of that meme where a cartoon character is in the fridge stuffing his mouth and the top caption reads "anti-gay preachers when no one is looking" And then the bottom caption reads "COCK"