It’s an interesting thought experiment. Why I would say to kill all pandas is because I’m almost convinced that Pandas are a human creation. Also, even if they aren’t, they’re going extinct; whether by us or otherwise. And if they are meant to go extinct then they should be let to do so. This experiment would highly accelerate that, but still.

Also, the experiment is hypothetical and mostly silly, so my answer is allowed to be also. I don’t put much stock in pandas. They’re cool looking but they’re kinda dumb.

I think the magnitude of effect there will be is based on proximity to the subject that dies which might actually average out to there being no clear utilitarian choice.

And if you were to start narrowing down criteria for which human dies than it’s no longer random. It’s selective. And that is not good.