In this note: HIGHLY recommend “Rigor of Angels”, which (in part) details Heisenbergs life and his moral qualms about building a bomb. He just wanted to be left alone and perfect his science, and it’s really interesting to see how such a laudable motivation can be turned to such deplorable, unforgivable (IMO) ends.
Long story short they claim they thought the bomb was impossible, but it was still a large matter of concern for him as he worked on nuclear power. The most interesting tidbit was that Heisenberg was in a small way responsible for (west) Germany’s ongoing ban on nuclear weapons, which is a slight redemption arc.
Heisenberg makes you think, doesn't he? As the developer of Hitler's bomb, which never was a realistic thing to begin with, he never employed slave labour for example. Nor was any of his stuff used during warfare. And still, he is seen by some as some tragic figure, at worst as man behind Hitler's bomb.
Wernher vin Braun on the other hand got lauded for his contribution to space exploration. His development of the V2 and his use of slave labour in building them was somehow just a minor disgression for the, ultimately under US leadership, greater good.
Morals are hard in real life, and sometimes really fuzzy.