It's true that marginalised people don't always vote in the interested of people sharing their marginalisation - see any Republican in the closet who were always routinely voting against gay rights while still fucking dudes. That is, of course, their right - and can be seen as hypocritical. Of course, that's also expecting someone who is, in this instance, part of the alphabet, to want to vote for all the alphabet's interests, as if a) being gay is the only thing that matters about Buttigieg, and b) he has to support every group that has tied itself to the LGB bandwagon no matter what, whether it be troons, asexuals, or on and on down the line of all the groups that try to get in on the 'queer victim' ideology.
But also, that's not what the troon said. Strangio's basically saying, 'we're not saying Pete's the wrong kind of gay, we're just saying he's not the
right kind of gay'. They're trying to gatekeep what represents acceptable gayness while pretending that's the last thing they're doing.
Ignoring everything else, Pete Buttigieg is a man married to another man. He's gay. But they don't want a cis white man who wears suits and represents gay as normalcy, they want someone who is aggressively alternative, who provokes their opponents more and is much more marginalised.
Of course, that person wouldn't get elected - that person wouldn't even be in the primaries. But they're zealots who would rather complain than work for change, and it's profitable for them to be as marginalised as possible, so they have absolutely no reason to accept that. Whether they like him or not, Buttigieg is an unequivocal step forward for gay rights in that he can even stand on that stage without questions about his sexuality making him unfit to lead. But he doesn't give them more power by his representation - in fact it could be argued that he lessens it a little, because the more normalised the alphabet is the fewer oppression points they get.
And I'd bet the
vast majority of people trying to gatekeep him for not being 'their' sort of gay are younger than him.