To kill Hitler is the morally right thing to do, but to kill baby Hitler is wrong, subjectivity is why morality is so arbitrary... it's Immoral to own slaves, but African tribes have done it for centuries, do the blacks reperate themselves???? The world may never know....
@DiegoWolfe is it morally right to kill Hitler though? One could argue that any other intervention to prevent him from gaining power is equally effective and morally more acceptable.