My take on the topic at hand:
Chris Kyle - volunteered to defend freedom. Good. The man is a patriot.
Most confirmed kills by a US sniper. No way to judge. Is his number high because of his skill or because he never used moral judgment and took out every target without thought? Either way, celebrating death feels strange. The enemy has children, spouses, and or parents, many fight for causes they have been lied to about, but face a far stricter punishment for refusing if they disagree.
Turning soldier into celebrity is disturbing. Not a lot of WWII vets came home and wrote books or got radio/TV gigs. My grandfather never mentioned it to me or any of his kids or grandkids. Everything I know is what my grandmother told me. Our current culture has created this and I personally don't like it. I don't blame soldiers for telling their stories for a paycheck, many do it as a word of warning to incoming recruits.
Helping someone with PTSD by taking them to a shooting range? Not the brightest move. And this connects Kyle's story to the topic at hand for me.
People with mental/emotional health issues, including PTSD, need to be in treatment. We need to find the best way to help them. Their violent outbursts are a symptom of their suffering. Kyle was trying to help. It should have been done by our military, but in the absence of that Kyle stepped in.
The death of Chris Kyle was not the direct result of his actions as a soldier. He did not die by the sword because he lived by the sword (sorry, Ron Paul. We disagree here), nor did he die in battle. He died trying to do what our military should have been doing, helping a soldier scarred by his experience. This is no different than when other veterans would snap.
If anything, this helps my earliest sentiments after Sandy Hook. No amount of gun control will help when you have mentally ill individuals with the potential to snap unable to find treatment, much less even be diagnosed properly.