Germans,Austrians (and others) were executed for disobeying Nazi orders. That includes in the military as well as civilian administration. IMO there are some occasions...and perhaps many...where a *junior* soldier,or civilian,could almost be forgiven when claiming "I was only following orders".
It must be noted that among many...if not most...of the younger participants in the genocide the Hitler Youth played a huge role in their formative years.
Assuming that there's at least some validity in what I've said I certainly cannot be sure that that can be applied to Demjanjuk.
Your post highlights the many problems that occur when judging who is - and who is not - a war criminal. Certainly the Nazis who were on trial at Nuremberg were war criminals. And they deserved their fate.
But what about the guy who drove the train to Auschwitz? Did he deserve to hang? What about the guy who marched children off to the gas chambers? Did he deserve to hang?
What about William Calley, who was convicted of murdering 22 unarmed South Vietnamese civilians at My Lai? Did he deserve to hang?
As you noted, GSC, G_d will judge them all.