That is just not how leftists think at all. And no, the “leaders” of “the free Palestine train” are not anti LGBT or anti religious freedom, even the insane Hamas supporters don’t see them as leaders of their movement, the international movement is very separate from Palestinian politics in the Middle East, it’s lead in the West primarily Palestinian refugees and their descendants who tend to be more liberal on all those issues than even a lot of the Arab parties in Israel
The thing is most of these people you’re talking about don’t support these regimes, they just oppose US and Israeli imperialism more You’d be hard pressed to find much support for any Middle East government right now from even many of the most conservative among Muslim Palestine activists, let alone on the left
It sounds like you’ve spoken to a very limited amount of leftists, those kind of positions are very uncommon among leftists offline, as someone who has known many there’s only one I’ve known offline who had something close to that kind of position even briefly and even for him it was only in the immediate aftermath of Israel bombing Iran where his family’s from (he’s also Jewish and got a bit more reasonable after I talked to him, but that was his gut reaction)