I would expect a decent human being to 1) not put himself in that situation to begin with; 2) having inadvertently put himself in that situation, defend his life but to recognize the injustice of it, and repent - DEEPLY or, failing that, to respect the humanity of the life he just took, and MOURN.
Kyle expressed nothing of the sort. I completely understand that our entire society is built upon a particular paradigm which glorifies the role Chris Kyle played. Yet at a minimum, as a human being, before looking down range at another human being and pulling a trigger to cause their death, I do not think it is too much to expect a certain amount of introspection and reflection.
I pray for Chris Kyle, and sympathize with him; but I do not overlook his role in society, on a human level, simply because society has constructed an artifice which excuses his actions. His actions are his own, and he alone is responsible for them. To allow excuses for such actions is to go down a road all too familiar to statists and socialists.