There's a difference between a brain that developed and grew under a set of unusual physical constraints and a brain that developed normally that's been cored. The first is not normal but has not had chunks destroyed all at once after it was laid down.

I am reminded of the difference between patients born without a corpus callosum between the cerebral hemispheres and those that have them cut in adulthood. The latter develop classic split brain apparent semidual consciousness, the former are basically normally unitary (and diffusion tractography reveals an unusual density of sideways connectivity within the normally not very connected subcortical midbrain stuff, presumably built up in compensation as they built themselves, decidedly not normal nor as extensive as the corpus callosum but apparently functional).