This is a thing that I think a lot of leftists living in developed countries don't realize. While it's true that the left is stronger in the developing world, it's also true that a lot of them are more socially conservative in many ways and that helps them gain popular support. The leftist militants I know are pretty anti-lgbt and would be considered stupidpol types if they lived in the US, yet they managed to fight a fifty year war with the government and had strong support in the rural areas.

China is still a developing country--one that's rapidly developing--and that comes with the growing pains of cultural issues like this. They'll most likely have more favorable legislation towards lgbt people, but it's not happening overnight.