I'll forget Hitler if you'll forget Castro.
Trade the memory of one dictator, his friends and his deeds, for another. Of the two, Hitler and his minions were more culpable, just in the number of dead bodies generated let alone in other expressions of destruction, though people whose families were hurt by Castro will probably not see it that way.
If von Braun was not actively complicit, but merely someone who went along to avoid a permanent vacation in a concentration camp, the period's history will eventually clear him.
How can we remember if we forget? How can we forget if we remember?
"Wernher von Braun"