No, not true. The Bay Area is ideologically safer in only two regards: you can criticize the city, and you can criticize the government. If you have personal beliefs that are even a tiny bit different from orthodoxy, Beijing is a far safer place.
As long as you don't try to subvert the government or anything, you can talk about it.
Talking about it influences opinions, and when critical mass is reached, even autocratic governments sometimes are forced to abide by the consensus of their people.
Noone's claiming that China is a better or more progressive country btw, just that in this very specific regard, US is worse than China.
As I said in the rest of my post, I agree with you that there's more room for ideological diversity without being ostracized in many other places.