As a practical matter? You censor yourself. And/or practice the great art of Ketman [1].
Criminalizing points of view is harder to implement, as a practical matter, than criminalizing behavior that most people today see as actual, victimful crimes. There's no equivalent of "grass mud horse" [2] for terrorism, childporn, etc. As the Chinese government is very aware, even a well-censored network is way more dangerous to them than no network at all.