I don’t get it. You had what was the mass of everything compressed to the size of an atom. Densities that are unthinkable! Why did it not just form the ultimate black hole?
You get into trouble with this claim:
The mass of “everything” in the pre-inflationary era may have been as small as 100kg. Most of the current mass of the universe formed as the false vacuum collapsed and the universe inflated.
Because a black hole requires a section of space-time to warp. When all the mass took up all of space-time, there was no “surface” to be distorted past an event horizon.
On the other hand: If the Universe is closed, then one could fairly say that it did collapse into a black hole. The Big Crunch, then, is the singularity in the center. It’s just taking us a long time to get there, since the universal black hole is so big.
But the current data does not seem to suggest a closed universe, so that’s not really relevant.