Documented homosexuality is NOT pro-LGBT. Allowing rich and powerful men to keep male lovers or pay for male prostitutes is NOT supporting LGBT minority rights in any shape or form. Legal homosexual marraige was not a thing, and inheritance laws would never imagine such. Even emperors' male lovers were not recognized as their spouses or belonged to the harem; they always held formal positions at court and most of them actually had families of their own. One of the greatest moral failings according to classic Confucian ethics was the lack of progeny (not just children, but biological children who carry on your genes); what does that say about heteronormativity? You will be extremely hard pressed to find one full on gay man in Chinese records: every man with male lovers also had wives and children. Supposedly homosexual men don't look like they suffered all that much discrimination in ancient China, because women were basically nonbeings with very few legal rights and protections, so in comparison men didn't have much to worry about, even men who were in relationships with other men. Legally speaking the wife was not even entitled to inherit the husband's wealth unless the will specifically bequeathes wealth to the wife, so sure, no discrimination against a potential male partner there.
As for lesbians? A lot of the lesbian stories are basically about young girls, or prostitutes, or about wives/concubines who belonged to the same man. Two women of the same household might enjoy a peaceful lifelong relationship if their man happens to be into that kind of thing; if the man isn't into it then it's still adultery and punishable by adutlery charges.
It is really hard to apply Christian and modern stanards of what is anti- or pro-LGBT to a pre-modern polygamist society. In fact China's anti-LGBT tendencies today are perfectly in line with its historical actions (not an excuse as modernity has new requirements). No legal marriage, no representation in media, and no public talk of sex in general anyway. (It was quite fringe to portray homosexuality and sexuality in general in ancient China.)