This is actually wrong (Parker's bio goes into it). You seem to be parroting the neo-nazi version of Peiper. There is hard evidence that he ordered an American POW killed right in front of him. His command of KG Peiper was a big fail and his force only lasted over a week before being wiped out with most of men casualties. You may be forgetting that many SS wounded were with the Americans, and Peiper had good reason to radically alter his behavior. Peiper, although he was a convicted criminal & mass murderer of civilians and Soviet/American pows, had many friends in the SS that hooked him up with a good job after prison and it can be said that he was a "upper middle class" and then actually a well-off man who lived in a villa.
As far as his death, there is evidence that he severely depressed and then committed suicide. Get the Parker book if you are interested in the man.
You my friend are skewing history a bit with your own perceptions and perceived truths. There was no HARD evidence that linked Peiper to the massacres, thus why he was not Killed but rather served shortened sentence. His command of KG Peiper came on the heels of the distruction of the unit(Prior to being made a KG) while he was getting mediacal treatment. Furthermore He was hooked up with a job AFTER being pushed out of Porsche by an old SS MECHANIC Friend, not the normal SS Officers whom he had associated with during the war. He was well off because of his executive skills and ability to rise through the ranks.
I feel that both sides of the fence skew the truth that surrounds Pieper. He was a charismatic leader that also was skilled in playing the political game as well as the war game. He knew how to lead men and suck up to them. In the end my PERSONAL Opinion was that he was a skilled leader that had been brainwashed into the Nazi Ideology since childhood. However, I feel that there were much better officers to serve in the German military than him and that there is a sense of "AWE" that follows his name because of the Propaganda that was put forth by all sides.