Chris Kyle was awesome. The world is a lesser place because he is gone.
I dont know anything about PTSD. With that being said, I dont think it had a whole lot to do with what happened.
Personally, I think the sick ****** just wanted to bag a "big fish." In a twisted persons mind, what would be better than killing a legendary SEAL sniper? It would certainly give you notoriety. Everyone remembers who killed Billy the Kid and Jesse James (loose analogy but you get it).
Sorry, but a person doesn't shoot two people in the back, flee the scene in the dead mans truck and attempt to allude/hide from the police for 4 hours MERELY because of PTSD.
Glock 26 OD w/XS Big Dots
Ruger- 22/45 5", SP101 .357 mag, LCP w/crimson trace
Marlin 336/.35 Rem---Marlin 25N/.22 bolt gun