Wanderer - so I see that you agree to exceptions to your "absolute" codes yourself.
BTW, in my case, the question was "would you let the bum beat up the other bum", and my friend had to stop me from interfering. Another question was "who will give first aid to this injured bus accident victim". Of course no such question was asked, it took me about a second to leap for help, even if I have minimal first-aid training.
Philosophically, I have no problem of letting strangers die. I'm letting people die every day by not donating all my money to help people in the developing lands, and as hard as it is, I've come to accept that. When acting on instinct, it's of course impossible. Someone is still slower than the other one, and someone freezes completely.
Well, I ended up asked myself a question: "if you could, would you have this instinct of yours removed?" Strangely, the answer was still "no". Not because of strangers, but because of why this instinct has developed. If it was my own child (or anyone close enough to me) under attack, I'd be needing it, and for that reason only, I wouldn't give it away.
OK, you can call this an attribute of a hero if you want, and I'll even agree to it, at least until some point. But somewhere is that point where heroism stops and foolishness starts. Please, don't stand too much on the wrong side.