The entire point of surviving is to continue to promote humanity. How humane is it to stand idly by while someone is devoured by the undead? Not very. We will all be taking risks to survive and sometimes there are variables you could not factor in and will need help. Sure we could blame the victim, we are getting good at that in this society. Maybe they were unprepared. Maybe they were not cautious. Maybe, just maybe they are only in trouble because they got there before I did. Maybe I was minutes away from sharing their fate.
Generally if you are in the immediate area as someone who is in danger, than you are already in danger. His/her problem will soon be yours as they finish picking them clean. Granted their are extreme situations where you may need to put multiple people at risk to save them, but honestly that call belongs to each of them. There will be enough undead without me putting them on my conscience.