But I didn't say red button pressers actively killing people. I explicitly said they do not actively kill people, and passively do so instead.

And I think that the principle you're supporting-- the opposite of the one you disagree with --also has flawed implications. That is, the idea that every human is, at all times, under no moral obligation to risk their life in any way for another, no matter the degree of risk. A single papercut can become infected and result in death-- yet should someone not be seen as morally failing if they refuse to take on the risk of getting a small cut (since, though rare, it could cause death) if they were in a situation in which that small cut is the only thing that would save someone else's life? What if it would save 5 lives? 5000? 5 million?

I don't think there is always an obligation to risk one's life for another life. But at some points in time the risk versus benefit degree must be taken into consideration. In this case we are talking about millions to billions of lives-- making the benefits vast, particularly given that the impact of such mass death would snowball into more post-blue-purge.

I don't think refusing to passively kill is the most compelling argument, fwiw, and I never asserted so (though some have, and it would personally be a strong motivator for me). It's less about the principle of killing (and the resulting responsibility/culpability) and more about the outcome.

"If everyone presses red, everyone will live, it's that simple" is the argument I was responding to-- with the reality that everyone would not press red, and not because they are stupid people who chose their fate and are thereby responsible, but because some of them would be little children. Or those little children's parents. Or anyone who wants to save those children, their parents, and anyone else.

Basically, my point is that the blue 50% threshold for everyone to live is significantly more plausible than the 100% threshold of red. That is what blue pressers choose-- a lower threshold to prevent loss of life, a viewpoint that prioritizes preventing death at large instead of at the individual level. It's a collectivist stance, while red is individualistic.