I think it's still perfectly defensible, so long as you're equitable to all, and "other" isn't code for being a racist. Everyone should have access to birth control, family planning and advanced life opportunities. Everyone should have the opportunity to live a sustainable fulfilling life. That's often not possible if you're born into poverty, born to parents who didn't want you, or socially/culturally pressured into having children young.

The solution is better education, better contraceptive access & more sustainable economies that don't rely on endless growth that grinds human lives away for a pittance.

You twist what was said and then you say it is not defensible. Not cool.

There are two ways one can understand what you said and both are terrible takes.

You might imagine that everyone is somehow secretly racist/nationalistic/egoistic and somehow when they say we need fewer people they secretly mean that fewer of other “kind of” people. This is not true. When I say we need fewer people I include “my people” in that too, for whatever arbitrary grouping you would deem “my” people.

The other possible take is that you think everyone who thinks there should be fever people should commit suicide, or if they don’t they clearly mean “fewer other people”. This is also silly. In this context nobody proposes that we should get fewer people by killing anyone. People die. If you just stop making so many of them we will end up with less of them.

I had one kid, I'm purposefully shrinking the human population, I walk the walk.