The US Constitution, including the 2nd Amendment is the basis for authorities to pass any law. Any state or city that doesn't allow someone to defend themselves with a firearm, should lose their status as a city or state and be turned into a territory, with no electoral votes or members of congress.

The 2A Trumps such laws, and POTUS needs to remove any SCOTUS judges that can't understand that and replace them with ones that will uphold the Constitution.