It's hard because if you find it on a beach or a secluded area, you basically have no one to contact or give it too, and like I said even the act of giving it to someone could potentially compromise it. That's why I like the moral dilemma, it's very similar to the train track dilemma, basically whatever you do or don't do has some sort of consequence.
Maybe it is even harder than that!

There is much more uncertainty of the outcome, since private key can and cannot be backed up at the same time.

We must somehow mix the trolley problem and Schroedinger's cat to get a fitting image for this problem.