That's just an excuse to shift responsibility. In a kill or be killed situation, you could always choose to be killed instead of killing, you'd just have to sacrifice your life. It's just that people don't actually care enough to give up their life or any of their benefits.
It always comes down to the fact that people will not give up their own benefits for someone else. If you want people to do something you have to appeal to their self-interest, not their morality.