Do you agree that explosives/chemical/biological weapons can be defensive weapons? Even if it’s just explosives for the sake of argument.
For the record, government already has ability to take away your 2A right on the basis of mental stability, such as being declared clinically insane (correct me if I’m wrong on this).
I want to reference the fact that government isn’t a single agent and “uncle same” won’t be paying “some douche” who clearly doesn’t care about 8 years of his medical education and his clinical license to fake and misdiagnose somebody, is unlikely to happen.
Government is already doing plenty of testing on your to see if you’re fit to participate in things like driving. Granted it’s a privileged not a right, but in modern world that privilege has a much bigger impact on a person than whether or not they can have a 12ga, but government has complete and total control on who gets it, who doesn’t, stop you at any point in time (cops), reevaluate you and establish countless laws on the matter.