>the only winning move is to not play

Interestingly there are variants of the question where "no one pushes any button" should also be a "winning condition". The original problem states "if less than 50% of people press the blue button only people who push red survive" which rules this out, but it could be changed to "if greater than 50% of people choose red, then only red pushers survive" (allowing for people to opt to be a non-pusher). Or it could be "if greater than 50% of people choose red, then only blue pushers die" (with the non-pushers also being spared).

I think the latter is more interesting since now there's a moral consequence to voting vs abstaining.

Or you could lean into the political framing. I bet if the vote were retaken with question phrased as "if greater than 50% of people choose red, then people who pressed blue die", you might end up with some switchers who vote purely out of spite. Or maybe that framing makes it feel like voting red has a more significant moral consequence (actively condemning people to death) that the original question doesn't, so it results in more people pressing blue.

You could even add in a penalty if you press a button but are a non-majority, but then that's just the prisoners dilemma.