i don't think making light of some soldiers agony, even if they were on the other side, is appropriate.
was the war necessary? absolutely. did the vast majority of soldiers on the other side have any
choice in the matter? nope.
If he was SS then yeah the choice was his - not only that but he survived hell to become an SS trooper. As an SS officer the likelihood that the captured luger has a dubious past with regards to civilians, pows, etc is great as well. Not all enemies are honorable nor are all deaths.