Talk about moving the goalposts!
As a continuation of this thought experiment, I'm not sure we've made much improvement. The population of the world may be large, but it's not infinite. Some even believe its growth is slowing.
The easiest way to slow population growth, also the best for society at large, because it frees up more intellectual resources, is to educate women--particularly in those fast growth, less developed societies.
Continuing the thought from the previous writeup, distributing some of the plenty we now have to the second world and the third world would achieve two goals: slow the growth of population before it becomes infinite, and generate more of the truly infinite human resource--educated intelligence
I once believed the future of humanity lay in the stars--and still moved by fiction that portrays this. But I came to the realization that arguements such as this one are truly blind to the reasons why things are the way they are.
I remain interested in a true thought experiment that doesn't have its conclusion for its premise.
To move into space without taking a hard critical look at what we are, and how we got here, will leave us unchanged. It will leave us with a "fouled nest" at home--and we will take our fouling ways with us.
The frontier is an idea. We should realize that, and take the lesson.