Suppose that the "big bang" was actually a collapse - perhaps the collapse inside a black hole. Dimensionality collapsed. That would look to us (inside the black hole) like an explosion, but really everything would become much smaller, to create more state space within our new self-contained universe. A collapse in which the Planck length shrank, first like an implosion, and then more gradually. The region inside would become a new SO(3,1) system.

Perhaps the idea that the amount of information inside a black hole remains constant after its collapse makes no sense, because a black hole is causally disconnected from a universe that contains it - the amount of entropy inside a black hole has no reason to relate to the entropy of the system that created it.