Of course there are medical reasons. Whereas carabinoids and benzodiazepines (eg rohypnol) are detectable for ages afterwards and very easily byr the most hamfisted lab. I know this is a rumour board, but this poor guy has been ridiculed around the world, accused of being drunk, and unless you are really claiming someone falsified the results and the lab(s) allowed this to happen, you are being highly disingenuous to a fellow pilot.
I do not know what this part of the world is like, but where is the evidence of foul play? Surely the issue is that this poor pilot has had his career removed without, it appears, a diagnosis. If he has been told he cant get his medical reinstated when we dont even have a cause then I would have thought there might be a teeny bit of outrage amongst his peers....