during the flight Hempel, a well known (to CASA and also to an awfully large number of commercial and private pilots around Australia it seems) epileptic, who had previously had his commercial pilots licence cancelled by CASA because
Barry's suspected epilepsy wasn't "known to a large number of people" - it was a feature of the enquiry that those very few who
did know of it felt constrained by
medical ethics not to reveal that knowledge. I'm certain Barry didn't go about telling people of it.
As far as I know, his commercial pilot's license (CPL) wasn't cancelled, his class one medical was suspended (which should prevent commercial operations). This is an important point, because Australian licenses are stamped "Permanently Valid", so anyone asking to see Barry's CPL could be shown a valid license. Anyone asking to see his medical could be shown a valid medical - you would need to be able to pick up the difference between a class one and class two medical to know whether he was correctly licensed for commercial operations.