This, in all likelihood, is not this dude's first head trauma.
I don't have a good answer to our country's long-standing debate over gun control. I don't actually have any interest in owning a gun, but I have even less interest in somebody telling me I'm not allowed to own a gun. I have no idea what the various cut-offs should be for who should be able to possess how many of what kinds of of firearms after how much time and with what level of clinical insanity. I'll leave all of that up to the politicians to fight about until the heat death of the universe.
That said, I think that there should at least be a one-question test for gun ownership. When you go to buy a handgun, the salesperson should ask you if you intend to load it with a .510 caliber cartridge made for elephant rifles. If you say yes, then you don't get a gun.