No, they don't arrest people for such abstract concepts. They do arrest people who tangibly threatens the government, like exposing the shenanigans of high officials, or organizing labor protests over the Internet.
Haha, you would think that these cases count as enough evidence for the government not to have any power over speech. Nope. The Chinese people just oppose those specific cases, and in a small percentage of them, the government reversed course and then the masses are satisfied.
After those happened, they still think that the government intervention of speech is a good idea. The only problem is that a small group of officials not handling the regulating power correctly. But if they were to adopt the American model, how could they be protected from the evil influence of foreign adversaries? You know, like me, an agent of US propaganda. Or Tencent, whose major shareholders are actually not Chinese.
I really can't maintain a straight face hearing Americans repeating that same argument.