President Andrew Johnson issued an unconditional pardon to Confederate war veterans in 1868. He decided that it would be better for the country to try to move forward instead of harping on the sins of the past.
I think too many commenters are overlooking this fact:
A court decided that by being a worker at a concentration camp he was guilty of being an accessory to murder. This meant that courts did not have to prove active participation in killing to find a suspect guilty of murder, BBC Berlin correspondent Stephen Evans reports.
This is an outrageous expansion of how we judge people culpable and secondly it creates a crime and a punishment for acts committed which were not crimes because this law didn't come about until much later.
This is akin to arresting all liberals and charging them with human rights violations for supporting the Civil Rights Acts of 1964 and 1991. Huh? Oh yeah, at some future point some court decides that people who supported these Acts and followed the law are now guilty of stripping people of the right to free association by forcing them to hire people that they didn't want to hire.
Changing definitions of law, making up new laws and applying them retroactively is freaking evil.
What you wrote is false. None were forced to be. Any German soldier could refuse to participate and if so they would be transferred out. Because the genocide was not formal German policy they would not court martial any German soldier who refused without a trial that would put such actions on record. Until the end, the German military had very strict protocols including for court martials.