You know, spouting transhumanism would be far more socially acceptable if you didn't answer the legitimate questions spawned by mild transhumanism with severe, world-dominating transhumanism.
For instance, words like "world run by single intelligent entity" carry an extremely high prior chance of denoting an incredibly terrible idea. At the very least, you've taken something that was already an argument, statements that already required justification, and "fixed it" by appealing to statements that require far more justification. Basically, you've answered "Won't the elimination of aging cause a population boom?" with a combination of "Not if we do it in the way that most easily allows Malthusian population booms!" and "Not if someone I approve of is made Dictator of the World."
And, of course, your next line is that your planned Dictator isn't even a human being in the first place. While I fully know where you're coming from on this point, it still requires far more justification and explanation than either of us can give in an HN comment, and should a priori be considered a bloody terrible idea.
It's my guess that anti aging will happen slowly, and hopefully we can also slowly make policy changes over that time too. I just don't see the default answer of "don't worry, we have a process to go around killing people" to be acceptable.
But if the point was to say that major changes in the world could have major negative consequences, yeah, sure. Maybe they aren't solvable. But just don't pretend that Natural Death is OK because it's slightly alleviating one problem.
But the idea that it's more acceptable to torture nearly every human on earth because "you live, you die" - that sounds like, at best, a local maxima. And even if there were insurmountable resource issues, we should still not hand wave things, but any explicitly admit our policy is to permanently destroy people, look them in the eye when we free their resources. Like a real world OOM killer.