Every time I've heard a story like this, the comment of "why didn't he just kill him?!" usually shows up in one form or another. It's easy to think about from afar, but I think people don't realize how hard it is to kill someone. I mean emotionally. I heard some similarly story recently, and in the end I'm pretty confident that the victim doesn't dwell on why he didn't kill the guy, but is probably relieved that he doesn't have to live with that on his conscience the rest of his life.