The whole point is that if you accept the fact that expanding population is good a priori, this leads to stupid conclusions by the tyranny of exponential growth. Who cares if the average person is a slave when you have several hundred billion of them. Who cares if mothers die horribly after being forced to carry child after child.
Personally I think the only consistent viewpoint is some form of logarithmic population * average well being metric to measure utility. From that perspective, I have no clue how a policy maker should act today. Hopefully smarter minds than mine figure it out!
Maybe if you're evil enough to not care about any individual human's quality of life. Is there a word for the logical fallacy where you argue against the most absurd possible interpretation of a person's beliefs in order to feel no guilt for disregarding them?
This is the standard issue with any aggregate utilitarianism theories of morality.
https://utilitarianism.net/population-ethics/
It's a stupid idea that's been soundly rejected because it posits arbitrarily bad living conditions since "anything" is better than nothing.
In your world governments forceably breed humans like chickens in massive factory farms churning out people to the carrying capacity of the planet. I don't want to live there and I sure as hell don't find it moral.