This looks like the verge of a witch hunt. In the hell that was Nazi Germany, who wouldn't want to clamber up from the pits of Hitler's fury in almost any way they could, though short of committing murders themselves? It sounds very honorable to refuse out of principle, until you really are there.
He volunteered for a job as a guard in a death camp so he wouldn't have to risk death on a battlefield fighting in combat.
He wasn't ordered to work there - it was a plum assignment away from the fighting that he was lucky to get.
Germans who disagreed with the Nazi Party on principle did not join the Party - as SS men did - or volunteer for the SS either.
They got drafted into the regular army and served on the front.
He’s being extradited to stand trial. I assume it will be a fair one, and that he will receive a just sentence if found guilty, and allowed to go free if not. At 89, the extradition and trial may very well kill him and make the whole exercise a moot point.