This is the piece from the LINK in the OP that made me go, "Huh?"
Mr. Grant said a brain injury would interfere with a lawyer’s ability to multi-task, to concentrate, organize and express complex thoughts.
“That might not prevent them from working in a factory, it might not prevent them from lots of jobs. But it might completely stop them in their tracks from being a lawyer,” Mr. Grant said. “You could have the exact same injury on someone who cleans pools for a living and there is zero loss of income.”