You can't have local governments dealing with mutants who cannot be assessed accurately as threats because of Federal laws governing the privacy of medical records.
Yes. When you think about how often this happened in the past, when there were MORE guns and they were simply a part of the culture, and there was less FedGov involvement, it’s easy to see a possible cause.
Of course there are other causes as well. But it’s not about guns. It’s about the culture.