Sure, I understand what you're saying Remoak about being sudden etc., and I agree in this instance it is highly unlikely that it was gastro and this poor bugger will more than likely loose his medical for life. But consider the following scenario. You're flying in the outback, it's a 3hr flight, with very little choices of landing points along the way that would be able to provide medical assistance once on the ground.
In the few of hours before the flight, you're feeling a bit off, but put it down to maybe just being a bit de-hydrated and hungry. You drink up, have a bite to eat and think you'll be right in the next hour or so. Meanwhile, it's time to leave, you jump into the aircraft and off you fly. Half way into the flight you're really starting to feel unwell now. Maybe that curry you got from the Mindil Beach Markets last night wasn't such a good idea after all. You're now rapidly going from just a bit of a pain in the gut, to severe sickness.
You have a look around and find a major town close by that will be able to provide medical assistance. However you're now starting to feel faint, throw up massively, and pass out for 30 seconds or so (I have experienced severe gastro before where I did pass out. Thankfully it wasn't while I was flying!). Thankfully you wake up, decide that town close to you is a pretty good option now and you divert and make a safe landing to be met by medical personell on the ground.
Surely if the above situation transpired, and it was clearly evident that the sudden onset of severe gastro was the cause, they couldn't take your medical away from you? Hopefully common sense would prevail, but seeing it's CASA, that's not always possible,
.
morno