You keep addressing the behavior of the police. I would ask you to take them out of the equation hypothetically.
Tell me what you think of the behavior of the youth. When asked to show ID, which he refused to do, when asked to leave which he refused to do...was his behavior and language appropriate?
That a citizen feels so entitled that he does not have to comply with the rules or laws and we obfuscate what is really going on here by focusing on the police...it boggles my mind. This kid is seriously in need of counselling. His oppositional defiance is as much out of line as any aspect of the police response. I think even more so. The kid is responsible for his behavior. There needs to be consequences for his actions. He should be barred from the library for the academic year. He can go to the city library. Odds are, only the police will be condemned and pilloried, while the kid will be made a hero. Pretty sad.