You guys are getting ridiculous. You began by claiming that the Lunarians are dumb because they rejected the Hourai Elixir even though it made them immortal, thinking that the only point of eliminating kegare was to live forever, which it isn't. Purvis points this out and relates it to charity because a total lack of kegare is the goal and staying clean yourself and cleansing other things works towards that goal. You say it doesn't compare because they talk of eliminating humans to do so (which they wouldn't actually do anyways), but that doesn't matter at all. The mindset isn't about "saving humans", it's "keeping the world free of kegare". Of course when you come from the perspective of "eliminating humans is bad", eliminating humans is bad, but that doesn't matter because that's the wrong perspective to begin with. Nothing about your arguments here have come from a proper understanding of the material you're trying to criticize.
Again, this is why I started talking about greenhouse gases, because it should be something you can grasp more easily. Surplus of greenhouse gases causes drastic changes in the planet's climate over time, and hey we need to reduce emissions to save the planet. But if human lives themselves generated the greenhouse gas, obviously one solution is to just get rid of humans altogether, even if that's a drastic measure. Kegare, by comparison, is what causes everything to "degrade" over time and die, invites disease, depression, misfortune, etc. It isn't arbitrary at all, unlike how you seem to be portraying it. If it was as arbitrary and human-specific as something like skin color it wouldn't be meaningful or interesting. Nobody is actually defending the elimination of all humans, but you need to step outside your box and at least recognize that from this perspective, the reasoning makes total sense and isn't particularly problematic.
If you don't understand that they're absolutely correct from the point of eliminating kegare, the whole dynamic is thrown out the window and nothing about Lunarians makes any sense. The whole point is thinking that the Lunarian perspective is warped and recognizing the Capital is a dystopia, and the works themselves do a fantastic job of illustrating that in many ways. So much of the criticism surrounding Lunarians is from people not understanding one of the core foundations about them and reducing them to a one-dimensional "lol we're better than you because reasons" land of strawmen.