The poll is flawed because it presents your only option as shooting the guy in the head. If you have a gun, and have a shot at him, and you have the skill to shoot him in the head at will, you could (a) shoot him in the leg to keep him from making it to his target, and/or (b) shoot him in the arm/hand to keep him from detonating. Thus if there's any doubt, there's no reason to take the person's life.