I agree in principle, although in practice this is impossible to be preached. In China it's that political opinions aren't tolerated, especially anything that notes on the edge of separatism. In America it's the same, certain racial, gender chats are simply taboo, whether it's personal or national level. While there is no explicit governmental prosecution, you can be sure that you'll be punished in a way.

The idea is that in America such topics are prohibits because there is the idea of historical injustice and bringing everyone to a fair level for a "better society" (very well-intended). It is no different in China when political topics bring an uprising flux of emotion from within the Chinese people (also very well-intended in the context of Chinese legacy). There is no fundamental difference, only a difference in how the freedom of expression is backed by historical context and reigning ideology.