Good points, though I think cooperation benefits the ethical outcomes for both sides.

If we all work together to make sure that as many people press the red button as possible, then we can minimize the damage. The problem with the blue campaign is that the outcome gets progressively worse until it gets to the best outcome. 49% mortality is high and terrible unless you are very sure that the red campaign is going to lose. The ethical take on the red side is to minimize blue votes to zero.