The fact that this kid joins anti-government militia extremist groups and wants to be a cop is proof that many people don’t become cops to help people. They become cops because it’s a job where you get to carry guns and bully people.
There’s no genuine ideology in these people. If there was, he’d abhor the police as being an instrument of the state. If his anti-government beliefs were anything more than a thin excuse to run around with guns and body armour, he’d be strongly anti-police. The police are the most concentrated form of government there is.