We can argue the point of Peiper being a war criminal till the cows come home. As you said, it depends on whose standards you are using. He was not hanged as many of his subordinates were, and it was never proven that he was present at Malmedy during the massacre.He himself said he was not there, but had moved forward. A trigger-happy tank gunner opened fire on our helpless soldiers and that started it. That man that opened fire
never spoke about his actions, and he lived a long life.