The system is chock full of holes, some really big.
I had to wade through a lot of extra effort when I applied for my CCW permit because I had been arrested on a bad check ($5.00) 48 years ago. The warrant was issued in one county and served in another county some 200 miles away.
Had the CCW gods not been on my side and had both counties not had records nearly 50 years old I would have been denied the permit. The check charge and arrest were both in Alabama and they had copies of the original documents. They provided them for $5.00.
This guy should never have been able to access to a weapon, but denying thousands of others the right to possess and carry a weapon is not the answer. Or if it is then we're asking the wrong damnned questions!
That isn't what bothers me. He bought it legally. What bothers me is that he was clearly a nutcase and nobody was able to do anything about it. As a society, we are too tolerant of nut cases.