How could I have convinced this gay acquaintance that being gay doesn't mean you think like a woman?

This was an acquaintance from long ago. We’d occasionally see each other at functions. Almost invariably he’d point out a cute young man and say something like, “I bet you’d like to hit that! I know I would!”
I would be like, “Are you insane? He’s almost young enough to be my son. That’s gross.”
He was convinced I was lying, that I secretly wanted to have sex with every attractive man / boy I saw. He claimed to know this because he was gay and so he knows how women think.

What would make him think that? And how could I have convinced him otherwise?

It’s been a couple of decades since we’ve crossed paths, but I remembered this so I thought it would be something to talk about.
PS I know a few gay men today, and none of them claim that.