Any story that presents the question “Is it okay to kill someone to prevent their future wrongdoings?” and then answers it with “Yes, why are you hesitating?,” is terribly cynical and bleak. Even with Greek tragedies like Oedipus Rex, the narrative lesson isn’t “Oedipus’ father should’ve just killed the baby himself,” it’s “If you act to defy a prophecy you will make it happen.” The lesson of TLJ for Luke isn’t “He should’ve finished the job,” it’s “He shouldn’t have ignited his saber.”