This is, as I said, formulaic for this sort of science fiction --- think of Bear's ``Blood Music,'' or even Childhood's End; I was expecting something along these lines from nearly the beginning. Still, it really doesn't fit with the premises of the novel; there's no good reason why the mycora should record the personalities of humans as it metabolized them, much less (so to speak) play them afterwards. The only idea I can come up with which even begins to make sense is that the mycora were deliberately designed to do this, but there isn't even a hint of this in the novel. Frankly, if McCarthy had to make the mycora intelligent, I'd have preferred, and much more easily swallowed, some utterly unfathomable and alien intelligence à la Lem than Yet Another Secular Afterlife. And why make them intelligent at all? It's not like they need to think.
Some more technical quibbles and spoilers, all pretty minor:
On pp. 5--6 the mycora are said to utilize the waste heat produced by UV lasers hitting them. This is thermodynamically possible only if they have a heat sink at a lower temperature they could couple this with, which I suppose is possible, in the circumstances described, and if they were already adapted to perform this coupling and extract work from it --- a damn odd adaptation. I have a vague recollection that this is later said to be a misunderstanding on Strasheim's part, but can't now find such a passage.
Twenty or thirty years is probably too little time for the refugees in the asteroids to have developed a genuine creole, if indeed creoles ever form in literate populations.
The stuff about cellular automata is rather peculiar. While I appreciate my field being boosted this way, there are already many CAs which make much more biological sense than Conway's Game of Life (some collaborators and I are responsible for one modelling the growth of bacterial biofilms, as found in sewage-treatment plants and on our teeth); starting from Life would be perverse. Then, too, as McCarthy describes Strasheim's ``Mulch World,'' it would demand more computational power than probably exists in his entire solar system, outside of the mycora themselves. (For the edification of my fellow CA-wallahs: it involves at least 22 bits of state (p. 175), encompasses an entire three-dimensional solar system, and is to be run on a serial computer with real-time display.) Strasheim needn't have slowed down Mulch World to delays its collapse into quiescence; he'd be lucky to see it start.
And why on Earth, or Ganymede for that matter, do they need human shoe-makers in the Immunity? You don't need AI to automate making shoes, even customized ones.