In a former life I was a cognitive neuroscience researcher.

This reads like a piece written by someone who heard a neuroscientist take issue with the "brain as computer" metaphor, but didn't quite grasp what it was all about.

The "brain is not a computer" meme has to do with the fact that the brain does not process information in the same way as a digital computer. It is not saying that the brain is not a symbol-processing/computational system.