Sounds like you completely misunderstand what a police state is.
A police state does not require the police to be concerned with upholding the law. In fact there is usually a departure from the rule of law in police states.
As the other commenter mentioned, the police in a police state are usually concerned with maintaining order and protecting the power of the state or ruling faction, and policing people's behaviour to this end.
I mentioned the anecdote because it's the one case I personally experienced where the police actually got active on an issue, and nothing came of it. I know plenty of people whose behavior looks like it'd be policed (censorship circumvention is endemic, discussing events that reflect negatively on the government is common, some openly advocate e.g. for gay rights) but there's no indication the police are even aware of them.
I don't deny that e.g. forming an organization directly challenging the CCP's leadership would get you into deep trouble, but most activity below that threshold appears to go unpoliced. Even the currently ongoing student protest at Beijing Normal University's Zhuhai branch doesn't seem to have met any police resistance so far.
A police state does not require the police to be concerned with upholding the law. In fact there is usually a departure from the rule of law in police states.
As the other commenter mentioned, the police in a police state are usually concerned with maintaining order and protecting the power of the state or ruling faction, and policing people's behaviour to this end.