The vast majority of police pilots in the USA are fully sworn police officers. All the pilots at LAPD are sworn officers. If a law enforcement pilot sees an aircraft being operated in a reckless manner in violation of the law and ignoring air traffic control creating a hazard to air navigation, the officers have every right to request the person land and investigate the pilots fitness for flight. In fact, they would be derelict in their duties for not doing so. If they ignored this guy & mid aired someone, people would all be bitching how lazy & negligent the cops were.
As soon as this guy landed, he took off for the closest bar and had a few belts before the cops caught up with him. This was most likely done to cover up the fact he had been drinking. His defense is that he only started drinking when he arrived at the bar. Possibly difficult to prove otherwise. Certainly not the actions of an innocent person or any professional I'd want in the sky around me.
I'm amazed at how easily some people can ignore the big picture for the sake of bashing the police. If law enforcement "asks" you to do something, it may just be a request but on the other hand there may be some facts you are not aware of behind that request & it could very well carry the full force of the law.