I suggest you should read up on the far more recent case of Fred Hampton and COINTELPRO regarding US "protection of dissent". American institutions protect the status quo and allow "safe" dissent (meaning bounded (e.g. NY Times) or ineffective (tiny groups / grandpa screaming) dissent). However, free speech is treated more seriously here than most other places and times in history, that is true and good.

https://www.zinnedproject.org/materials/assassination-of-fre...

That said, what is being done to the Uyghur people in China is vile and is contradictory to established human rights. It is completely appropriate to take China to task at the UN. However, as US citizens, it is difficult for us to have a strong moral voice given the wars, assassinations, coups, and destructive sanctions we have initiated along with our history of indigenous genocide, colonialism, and slavery that we have still not fully reckoned with. Even now we are implementing a slightly different version of the Japanese internment camps for the most vulnerable people in our society, undocumented immigrants, to distract from the economic depredations of the ruling class.

If we want to be a more effective and just nation, we have a lot of work to do at home.