I actually agree. It seems there was no other time in recent history when we were truly in the right about so many things. I believe there are some passages in this document that touch on this:
"HAHN: I must honestly say that I would have sabotaged the war if I had been in a position to do so."
"...They then went on to discuss the feelings of the British and American scientists who had perfected the bomb and HEISENBERG said he felt it was a different matter in their case as they considered HITLER a criminal..."
"WEIZSÄCKER: Our strength is now the fact that we are 'un–Nazi'."
Many of the physicists mentioned here expressed doubts about the Nazi regime. Perhaps it could be said that they didn't achieve the bomb because, in many ways, they didn't want their leaders to possess it. So there was a kernel of doubt preventing them from doing so. On the other hand, the Americans did not have that problem since they "considered Hitler a criminal" and viewed it as imperative that they win the war at any cost. Maybe this made the moral question of whether or not to achieve the bomb less of an obstacle for them. That gave a psychological benefit which facilitated the work they were doing.