The main part I disagree with is the claim that resource shortages may halt or reverse growth at sub-Dyson-sphere scales. I don’t know of any (post)human need that seems like it might require something else than matter, energy, and ingenuity to fulfill. There’s a huge amount of matter and energy in the solar system and a huge amount of room to get more value out of any fixed amount.
(If “resource” is interpreted broadly enough to include “freedom from the side effects of unaligned superintelligence”, then sure.)
I am inclined to agree, but it seems plausible to me that the transition from planet-wide economy to Dyson sphere may be slower than the earthbound economic boom that makes it possible. I don’t really see a plausible way to disassemble the asteroid belt and maybe a few planets days after Earth figures out how to start expanding into space at scale.
The problem is that access to the entire store of matter and energy runs through the single thread of successfully scaling space travel. So the logic appears to run similar to Dissolving the Fermi Paradox; the question largely reduces to whether one or more of the critical choke points fail.
Space travel successful → almost certain growth
Space travel fails → almost certain doom