I feel like the quotes agree with parent:

> “If something happens very slowly over quite some time, maybe over decades, the different parts of the brain take up functions that would normally be done by the part that is pushed to the side,” adds Muenke, who was not involved in the case.

Did you see the scans? The dude's head is practically empty (brain 55-75% smaller than normal) and nobody even noticed until he was 44 years old and got an MRI.

I think it’s that a priori you would expect a hollow brain to have a far more drastic effect and not allow for a mostly normal adult life.

Why would you expect that, when a tiny insect can do pretty intelligent things? What "unexpected" things humans can do are probably all in the >75 IQ range.