There is a lot of information online about how foreign visitors must register with the police at every city they visit. If you're staying at a hotel, the hotel will do this for you. That's why you can't stay at all hotels in China because some don't provide this registration at check in. This is not a new law. If a foreigner violated Chinese law in the past, they have every right to refuse entry. That people slip through doesn't mean that they don't care if you violated this law. It might be useful for him to post a video warning people that they must register with police if staying at an Airbnb or private residence or face the consequences. I don't think he should be so outraged regarding his experience since he himself is to blame for his own negligence.