The request was not stupid.
Go to a restaurant tonight with some friends, stay til closing, and be an outspoken jerk when you're told to leave. Then, when the cops come, keep acting like a jerk and refusing.
Tell them "get out of my face" seven times and you're "I'm almost done with my conversation" and then you'll leave.
That will help you figure it out.
It's called disorderly conduct, a law on the book in every state.
I am not sure why you, an adult, find this hard to understand.
The official Alabama Legislature website.
alisondb.legislature.state.al.us
(a) A person commits the crime of disorderly conduct if, with intent to cause public inconvenience, annoyance or alarm, or recklessly creating a risk thereof, he or she does any of the following:
(1) Engages in fighting or in violent tumultuous or threatening behavior.
(2) Makes unreasonable noise.
(3) In a public place uses abusive or obscene language or makes an obscene gesture.
(4) Without lawful authority, disturbs any lawful assembly or meeting of persons.
(5) Obstructs vehicular or pedestrian traffic, or a transportation facility.
(6) Congregates with other person in a public place and refuses to comply with a lawful order of law enforcement to disperse.
(b) Disorderly conduct is a Class C misdemeanor.
He was told to stop the music.
Not to play one final song (however long that was going to last...10 seconds or 10 minutes...)
To stop the music.
Further, the cops had no reason to believe the guy who starts defiantly with "GET OUTTA MY FACE!" over and over was going to comply.
In fact, the band director was signaling the opposite.
It's no surprise he later resisted arrest.