What the tu quoque arguments show is that the US' actions have nothing to do with human rights. The US cannot simultaneously support Saudi Arabia's war in Yemen, itself kill hundreds of thousands of people throughout the Muslim world in several different wars, and then turn around and pretend to care about the human rights of Muslims in China.

This is about the US' geopolitical struggle with China over the question of whether or not China will become an equal power with the US.

Tu quoque is valid in context of blaming Germans for WWII (past actions). Most of the arguments thrown here are about on going problems.