Overpopulation is clearly a problem, probably the problem, but you don't solve it by guilt induced suicide, mandated death or shipping people off to camps (not in the "civilised" world anyway). You discourage excess procreation. Tax after the first child, free birth control, and advertising campaigns should reduce numbers. After all many nations did all that in reverse to encourage more children, but they didn't make breeding compulsory. There is no hypocrisy in the stance. I'm sure there's other non-dystopian possible approaches that stay safely away from holocaust and eugenics.
The hypocrisy is pretending a finite planet has infinite space for expansion where we keep expanding until there is a catastrophic crash. Perhaps some wildlife will remain, perhaps not. Far better to have a controlled stop and seek to find a sustainable population - where earth can regenerate what we use, and we still have sustainable wildlife, insect, sea and plant populations and some wilderness.
Humanity keeps on demonstrating they can't do self-controlled, so your worldview wins. Future crash it will be then.
If the planet is overpopulated then that is a problem, regardless of whether people observing this fact or reaching that conclusion see themselves as part of that problem, and regardless of whether or not they take themselves out of the genepool to remove the hypocrisy.
IMO that’s the wrong conclusion to draw. Its just natural behavior. Its simply an argument for localism and accountability.
It sounds terrible I know, but it serves to demonstrate the hypocrisy of the stance. Like George Carlin said,
"I’m tired of these self-righteous environmentalists, these white, bourgeois liberals who think the only thing wrong with this country is that there aren’t enough bicycle paths. People trying to make the world safe for Volvos. Besides, environmentalists don’t give a shit about the planet. Not in the abstract they don’t. You know what they’re interested in? A clean place to live. Their own habitat. They’re worried that some day in the future they might be personally inconvenienced. Narrow, unenlightened self-interest doesn’t impress me."
* note: don't actually do this if you believe this wretched, damned worldview, go seek help, I don't really want anyone to off themselves because they think it "helps the world"