Overall, this is a thoughtful piece. You are trying to walk the line between those who want to blame PTSD for everything, and those who want to pretend it is just a species of moral weakness.
As I think most reflective people will realize, all of us are some combination of our heritage, our history–genetic and sociopsychological–and our individual wills. I think all of us are born with predispositions, which are further shaped by our decisions, which I tend to term “non-statistical coherence”. By that, I mean that individual agency can disrupt otherwise dominant patterns in ways which are greatly muted in lower animals like dogs, and absent entirely in animals like insects.
In this particular case, we need to understand that PTSD is not a single, unitary disorder, but a complex of tendencies created in a normally much more pronounced way in vulnerable individuals via combat than many other sources. Being the son of an abusive alcoholic is not fundamentally different than going through tough combat situations, but if you combine the two, the net effect will no doubt be larger.
In my considered view, we need to increase the mental health of our nation across the board. This would include work–such as the meditation exercises the Marines have been experimenting with–that works to inoculate against the accumulation of stress. As a nation, we need to learn how to relax deeply. Virtually our entire culture works against this currently.
Finally–and yes I grant this is a bit meandering since I am thinking out loud–I would submit that the shooter, who according to reports I read was a Marine, did also at one point in his life sign a contract to protect and defend the Constitution, with the understanding that it might cost his life.
We don’t know who he is, or what makes him tick, but we DO know that a common outcome of prolonged combat is increased issues with anger. Yes, they may be increased relative to preexisting issues with anger–combat seems to find character flaws and amplify them–but this shooting would likely not have happened had this man never signed that contract. That is speculation, but likely in my view accurate speculation.
His life is over too. If he goes the Timothy McVeigh route, he will be executed in relatively short order. Certainly, he will be behind bars the rest of his life. I do not think it is pushing my logic too far to call him a combat casualty too, although of course I am open to further information.
Actually, one more note: if you have not read it, I suggest you read Judith Herman’s “Trauma and Recovery”. It was very eye-opening to me. A case can be made that exposure to combat is not all that different than exposure to rape. It is a trauma; some people deal with it without issue, but others don’t. A variety of factors affect what that outcome is, and some of them can be named and measured.