This doesn't make any sense to me. I know they aren't Marxists, but the goals of communism are people-centric. We're trying to achieve a better society for all people, so why exclude certain groups from that?
Part of it is this idealistic adherence to "materialism" that rationalizes existing oppression with Marxist rhetoric. Gay sex doesn't produce offspring, so gay sex must be unnatural and worthy of oppression, and since we see the liberal bourgeois culture being more accepting of queer phenomena, then it must be a bourgeois degeneration against the very real materialism that says sex is always between a man and a woman because science.
Not all factions of the bourgeoisie really care for LGBT people, and the ones that do are hardly capable of grasping queer theory the same way we do. They do fundraisers to feel like they're not imperialist monsters even if they fail in every other way to make our lives less horrible under capitalism.