Once the State gets to decide what is and what isn't offensive and base prohibitions on such, civil rights are essentially over. The article doesn't even say that he was playing the music loudly, just that it was audible outside of the car, which leaves a lot of auditory wiggle room. In most jurisdictions of the US you can be cited for disturbing the peace for playing your car stereo too loudly, but they don't get to take the content of what you're listening to into account, which would seem imminently reasonable. I can only hope that the local courts agree, and perhaps give the teen a chunk of the police budget for his inconvenience so that the lesson sticks.
_________________
Your boos mean nothing, I've seen what makes you cheer.
- Rick Sanchez