A lot of people are uncomfortable with the concept that the best possible outcome should be considered a crime.

(And I'm not limiting this to the circumstances under discussion -- I'm talking about the view that, no matter what situation you're in, there should be a way out that isn't a crime. Such people will, for example, object violently if somewhat incoherently to the fact that, under Qing Chinese law, a man ordered by his father to commit a crime had no way to get out of that situation while following the law: following the order is illegal, but so is disobeying the command.)

Note that people who object to committing war crimes are not a kind of legalistic automata that require following the letter of the law no matter what. We do not always decide something is a crime because there's a law that says so. For example, the Holocaust would have been a crime even if the powers at the time had decided that it wasn't.

Complicated Chinese (and Japanese) laws about legal and familiar duty are really not the subject under discussion here, but a red herring. Murdering innocent people is an entirely different matter.

Finally, consider there are many people in this world who won't commit some crimes -- such as genocide -- even if there is no way out and refusing will cost them their own lives.

> Finally, consider there are many people in this world who won't commit some crimes -- such as genocide -- even if there is no way out and refusing will cost them their own lives.

Yes, this viewpoint is more or less the opposite of the viewpoint I describe above, and it is also common. But so is the other one.