Just a thought, have you considered that (at least some, but likely most) straight men consider that to be part of their identity, so being seen as that feels like a good thing, while being seen as other than that may be distressing? This without having to consider that someone else's being gay is somehow less than.

I have no problem whatsoever with LGBTQ+ pride. I'm all for any decent (in the true sense, not in the false one that seeks to impose one's own morality on others) and ethical human being taking pride in who they are, as long as they extend the same privilege to all others, of being proud of their own identity.