1) He didn't indicate that he was not playing it for himself.
2) He definitely didn't indicate that he was making a public performance, nor was he playing it for the benefit of others.
3) The point is moot: this cop may have said one thing or another - but otherwise cops cay play this music for themselves which is obviously within their rights.
Your claim is nowhere near the statute, and you have nothing remotely near this in case law.
This isn't about laws or copyrights, because the arguments are ridiculous and embarrassing for these people making them - it's hardly worth pointing out.
It's about bias and populist delusions of the people who for some reason 'hate cops'.
It's really embarrassing for HN to see all this mental energy steered into anti-intellectual arguments and bigoted posturing.