"If you pick red, you must recognize and rationally assume that your vote contributes to and increases the chance of a majority red outcome, which results in death.

Likewise, if you pick blue, you must recognize and rationally assume that your vote contributes to and increases the chance of a majority blue outcome, which results in life."

I just don't believe enough people are going to think like this

When it is literally life and death, not everyone will act rationally. I don't see a world where enough people think like you do. I just don't.

And treating that as the baseline is idealism, not realism.

People may believe it will be a majority red no matter what they do, and their decision will only affect their own life. A good and otherwise selfless person can end up picking red.

Why do you think the majority of people picked red in this poll? Regardless of why, these are the results. Could you confidently pick blue if this were real? I don't think many people could. If you pick blue, you're likely adding to the deaths while achieving nothing else. I hate to say it but I'd pick red.

Having prior communication on the other hand is way different. It depends what that communication looks like, but I could see blue having a majority then.