My 85 year old father, a WW2 veteran, suffers from occasional nightmare flashbacks still from being bombed nightly in Europe. I'll not be critical of a person with this type of reaction to a horrific experience. How they deal with real life past this experience and away from their nightmares is something to judge.
BTW, I was raised by an uncle who was a Tank Commander in the 4th Armored Division (3rd Army, GS Patton) and went into Bastogne to 'relieve' the 101st Airborne in the Battle of the Bulge. He was later wounded (burned over 30% of his body) when his Sherman tank went up against a Tiger Tank w/that nasty 88mm gun - he never talked about the war.
That being said, and talking specifically about JF Kerry, I don't want a guy with flashbacks carrying the nuclear launch codes in his pocket.