For one thing, you may be underselling the homophobia in Islam a bit. And there's Tacitus, who says that the Germans punished homosexuals. That's a bit before the Christians, and it comes from someone from a culture not opposed to the practice.

Second, I find it hard to believe that the Chinese were turned homophobic, and remained so, by a few Christians despite millenia of tolerance, when the vast majority of the country isn't even Christian. It smells like bad historicism.