I have never, ever known anyone who wants an atomic cannon.
Many existing laws would prevent such an ownership, and these happen to be good things.
History will view Bloomberg as a combination of desperate power mania with a side-show, grifter mentality.
I'm not an expert, but a thorough brain scan could be a valuable diagnostic tool for Mister Bloomberg.
No, they don't prevent it. They make it unlawful. Besides, it's easier federal time to have unlawful possession of a nuke, than to get caught with crack cocaine.
Look it up.
Laws don't prevent things. They put a price on things.
That's what happens when you base your government on the gang shakedown model.