Just thinking out loud here:

Maybe it's really important to the future of humanity to somewhat reduce the human population. It's not just some green leftist bullshit that the Earth is in trouble. The oceans are way too polluted for instance and natural food chains worldwide are under severe pressure thanks to humanity.

When we manage populations of animals and don't let their numbers grow out of control, we don't do that because we want to do evil. We do that because we care about the long-term.

What's more ethical? Saving as many people in the short-term or is it more ethical to save future generations from an over-populated planet that will buckle under the pressure of too many human beings?