>>17142207being a lesbian is a sign of virtue. typically women are totally dependent on men, they cannot survive without them. If you can form a relationship without a men it means you are superior to other male-dependent women because you can survive without them. This is why famous historical lesbians are famous for being artists, soldiers, scientists etc. It's a bonus also because women aren't gross looking like men and don't get diseases like gay men. this is why so many bisexual women fail to become lesbians, they are too weak and dependent on men.
being a homosexual man is mostly negative because it entails that you are not a typical man. manhood is mostly about a certain set of duties, gay men for many reasons don't fulfill these duties. They are therefore breaking the provider dynamic for some reason. this can either be good (in both modern contexts, the great homosexual artists and scientists or in pre-modern contexts where they performed auxilary social roles) and bad (in the case where the homosexual man represents teh refusal to grow up or be accepted into the social dynamics of society).
in essence both are a break from social norms, the social norm of a man is to sacrifice everything for women and the social role of the woman is to accept a man's sacrifice. Therefore it is seen as ignoble for a man to be gay because he refuses his duty to sacrifice and noble for women because she refuses to accept the sacrifices of men out of dignity. this is Otto Weininger position anyways.