This sounds like a 'bacteria colony' analysis of humanity. It seems to me that by defining the hypothetical situation so narrowly, it is turned into a de-facto trigonometric equation, a graph function dependent only on the variable quantity of resources available.

It only sounds like a reasonable conclusion because of the ridiculous assumption that creating more people is a moral imperative, when in reality if people enjoyed a high standard of living they would choose when to reproduce in part as a function of deciding not to lower their own standard of living. Are we to understand instead that societal resources would be devoted to coercive baby-making towards fulfilling an abstract ideal of morality?!

Unborn babies are not immoral, so why should born babies be moral?