I'm not condoning for one second what he said, but this country was founded on the ideals of freedom and one of those freedoms was the right to be of different beliefs, even outrageously different beliefs. In fact most of our founders have very different beliefs than the communities they came from and that is in large part why they came here.
Where in the world is change and unhappiness never found? It doesn't happen and from a historical perspective these things go back as far as you can dig, they are not exclusive to our time.
I truly believe that gentlemen like this would not be so spun up if we were acting as a closer knit community. People act out when the feel defenseless and powerless. I think that reassurance that most of these anti gun proposals are probably going nowhere would help along with understanding that much of what may get past probably wont have a leg to stand on in the courts given recent decisions...
It could also be that he does have some sort of legitimate mental issue if we were a closer community then maybe would could help influence him to go get help. We are all human, we all make mistakes.