I bought and read the book A Higher Call over the summer. Good book and very thought provoking.
I don't know what I would've done in a situation like that. I thought it was a very decent thing for Stigler to give the Americans (clearly out of the fight) a fair chance to surrender. However, I don't think I could've just let them go knowing that is the enemy attacking my home and countrymen. This is touchy because I'm only stating what I would've done based on the advantage of being a spectator, but when the bomber crew refused to land, I would've put a shot across the nose to emphasize my point. Had they still refused to comply, I would've forced them down one way or another. At that moment, he was very reluctant to send the helpless crew to their deaths (what he felt was murder, not war) even though that was part of his duty. I don't think he thought the bomber was capable of reaching England when he broke off, deciding to leave them to their fates. I wonder if things would have turned out differently if the bomber was less damaged and he felt it was likely able to make it back home (and thus return later to bomb Germany again).
Had I been going through what he had, I could very well see myself making the same call; I hope I never have to find out. I was saddened but not exactly surprised that he received a lot of hateful criticism from his own people after the story went public.