The US does only care about China's genocides for selfish reasons, but the genocides themselves are not made up. The PRC is an empire, same as the US, same as the Soviet Union. There's a reason countries like Vietnam ally with America over China. China is a regional bully that's more of an immediate problem to them, despite all the terrible shit the US does. Just as Russia and the US have committed and continue to commit their own genocides, China plays the same imperial game.

Don't defend empires just because another one sucks. I live in one of these empires and never plan to leave, but I'm not gonna deny the truth about it while I legally can. I'm an American more than I'm any other cultural group, but I know how evil and rotten it is. I'll still live here and try my best within the empire while hoping people in China do the same.

China isn't socialist in the slightest, but even when it was, it was still a nationalistic empire. They've become more reactionary and dangerous recently along with everywhere else on earth. They played ball with the neoliberal system and beat the west at its own game. However, that system inevitably bred fascism everywhere and destroyed itself, leaving the world powers primed for war.

The big picture is that all sides suck. Even if you want to support one for practical reasons, carrying their water when you don't need to is pathetic. Be better.