I have no knowledge about songs being banned in the US or not, but I disagree with your assessment of laws being a waste of time. I’m not if favor of a police state whatsoever, but I would consider attending concerts of some right-wing rock bands as a first step towards radicalization.
Hence, preventing those from occurring where possible might keep gullible people out of the influence of radicals, or in the worst case, help keeping tabs on potential future offenders by being able to charge them with something.