I hate Nazis as much as the next sane person, but I fail to see why a German naval officer sinking commercial vessels should feel any more guilt than a British or American naval officer doing the same. And they did. And since the war was far over by this point, I see no need for propaganda.
As for afterlife ideas…it’s interesting but hardly profound, and anyone who would heed its message simply out of fear is a coward, not a wise man.