Re: Dear China,
"It's a good thing that none of the countries on "our side" also do those things, is it? Therefore we can criticise you with a straight face. (Quick look at the Middle East) Oops - sorry!"
I'm certainly not ok with e.g. US troops committing war crimes without punishment. Very few are.
Your argument can justify practically anything including genocide since most countries have skeletons in their closets (unwanted minorities, retarded, etc.) if you go far enough in history. There's no justification whatsoever for what the Chinese government is doing for the Uyghurs, their own citizens.