I definitely have a crybaby on my hands.
I haven’t spoken to him since he called the police, but I was as polite as can be up until that point. He asked me to turn down my music, and I did. And then he called the police.
I have no problems wearing headphones now if the music is going to be even the slightest bit loud, but I don’t want to encourage him in any way to continue his bullying. I have the understanding that the way to deal with a bully is to confront them (“call them out”, “call their bluff”).
I am also a big fan of the Rope a Dope strategy: give these people all the rope they need, and let them hang themselves (speaking metaphorically, of course). Somebody told me that Muhammad Ali used this technique; I don’t know if it applies here. If it does apply here, this would involve me continuing to do what I am doing, and maybe at some point if he calls the police, then the police will end up telling him directly that I am not doing anything wrong.