You're assuming your conclusion. There's still "a difference between being unaffected and dwelling on 'what might have beens.'" IOW there is a middle ground between sociopath on the one hand and endlessly rehashing important decisions on the other. It's actually a very large middle ground where you accept you did the best you could and you deal with the consequences. Oppenheimer seems to have gotten stuck in the "endless rehashing" end of the spectrum and Truman (and many others) think/thought less of Oppenheimer for it. None of which imply that Truman was a sociopath.