As background, the Waffen-SS were front line troops. Some of those divisions were conscripts (examples like Prince Eugen, 15th SS Grenadier (1st Latvian)). If you were Germanic in countries outside of Germany, many were conscripted into these SS divisions. Those divisions served on the front lines the entire war. If you were unlucky enough to be wounded, you frequently were sent to be camp guards while you either recuperated prior to rejoining your unit or never recuperated but could still serve.
So your choice was to die to avoid being conscripted or serve, and if you survived combat on the losing side and were wounded, you could choose to die instead of being a camp guard - these guards were generally used outside the camp on the perimeter. Pretty hard choices for a poor 21 year old farm hand from romania, lativa, etc.
Humans have a very strong survival instinct and many can and do things, that sitting in our homes in comfort seem easy to say no to.
Not saying what this guy did was ok, not saying he should be forgiven, but folks here should at least understand the situation. None of us know what we would do in such situations if we have never faced them - and I for one, have fortunately, not yet, faced such things in my life. If I ever do, I hope I measure up.
Was this guy wounded at the front lines?
One thing that struck me as I viewed the museum at Buchenwald was that the typical age of the guard at the camp was ~19. The Nazis purposely recruited young men from lower class groups into the SS guard ranks. Easy to warp their minds.