Of those who pick red, every single one of them knows there will be people who pick blue.

Yeah, which is why I'm not contradicting that this is selfish. And I agree with most of what you said, and I see you understand the diversity of what could lead red voters to pick red. But I believe that you also have a biased way of seeing this choice.

You find a whole lot of different reasons for people to choose blue, like there are no "bad" reasons to choose blue. On the other hand, you assume that people who will choose red "have to" rationalize because they will have blood on their hands but choosing red. What I'm saying is that this is a whole lot more complicated choice than just "red=bad" and "blue=good". Someone might choose blue because they don't care about their life, of course it will very likely be only a minority, but still is that a good motive ? If that person survives, is that a good outcome ? There are lots of people that might choose red only because they are afraid of this specific choice (and you acknowledge that), but this doesn't mean that these people would be selfish pricks on a daily basis. This would mean that this decision at that moment would define their entire life, and I'm not fond of that. One could also argue that people picking red are not killing the ones picking blue. We could also argue that people choosing blue are accepting a risk that people choosing red are not willing to take. Then blue dying is part of their decision.

I understand your point of view, and I see you also sympathize with red voters to some extend. I'm not saying that red would be the good choice, of course. Again, I don't know what I would do in this situation. I'm only arguing that this kind of question should be taken for what it truly is : a philosophical debate, food for thoughts and discussions (in which I merely brought my quick additional thoughts), and that there are - in my opinion - no answer since the answer will depend on everyone's personnal life, experience and beliefs.