If someone wants to film him, and then use the power of the Internet to amplify that video to be viewed by many, as is their current right, then they will simply have to do additional work to ensure they are not transmitting the officer's "tunes" to others. Take the time to edit the video provides a means to still publish. Not as easy as clicking submit, but still available as an option, without making a sensationalist claim that music is being "weaponized" by anyone.
People using straw man arguments to "weaponize" language and then place it online where it becomes divisive. That's more of a story than some dude using his phone in a clever way to protect from being video mobbed.
I am aware your comment may be sarcasm, so there's that.
A 16 year old working at McDonald's does not have the right to ignore the boss and play a gameboy (I was 16 in the 90's).
Banning music outside cop cars, or over the loud speaker, or on mobile devices while on duty does seem like something they definitely could do and would be within the law.