As I initially checked the Wikipedia article for Uyghur Genocide it took me about 1 minute to find that the article had his name spread all over it and the sources it cited. He works for the Victims of Communism Memorial Foundation, which is funded by the USA.
Every source you check eventually circles back to him. There is also not really any video or photo evidence, compare this to the terabytes of videos of the gaza genocide. There is like 1 or 2 picture that shows a prison and curled up inmates, this doesnt look good but still better than Guantanamo or the El Salvadorian prisons.
China accuses the USA of funding terrorists in that region, which also lacks good sources but given the USA track record of funding separatists for regime change for example in 1953 Iran "coup d'état" and the USA listing China as their enemy number 1 e.g. in their newest national security strategy paper, it doesnt seem too far fetched.
Yes this doesnt mean there cant be possibly any wrong-doing on the Chinese side but the evidence for that is scarce at best and manufactured at worst.
The one China policy is also a direct result from China winning WW2 against Japan, Japan used to colonize Taiwan and genocided the Chinese. Imagine questioning other results from WW2 like Polands indepence.
Also the british used to occupy Tibet and looking at other british occupations like Palestine or Sudan (with Egypt) it gets pretty clear that they left nothing but chaos. So given all this history it, to me, seems justified that China wants to keep their country together and looking at satellite pictures from Xinjiang we dont see rivers of blood like in Sudan or thousands of pictures of child amputees like in Palestine.
Its really convenient how in the West every separatist movement like Catalonia in Spain or the Reichsbürger in Germany is immediately not valid, why all separatist movements of the Wests "adversaries" are immediately legit.