Yep, that would be the baby universe in which I'm sitting writing this post.
This may seem extravagant, to explain why eggs produce omelettes but not the reverse, but he refutes all the simpler explanations.
It presently seems unclear, however, whether a de Sitter universe could even make baby universes, absent a better theory of quantum gravity.
Carroll's latest thinking tends in a different direction, suggesting that framing the issue within the spacetime realm may itself be a mistake; the true nature of reality may be Hilbert space with Schrödinger equation dynamics. Spacetime, with its arrow of time, may be emergent.
Strange that the weirdest ideas of modern physics - the MWI, emergent spacetime - seem to be the most plausible.
This is a fine book, and an excellent introduction for the smart non-physicist to general relativity, quantum theory (QM/QFT) and cosmology.