I wonder if the unfit for work notice was a triggering event for this disaster.
Couldn’t make a guess, but it seems he had plenty of problems and previous “unfit for work” notes that he also threw away. It may have been a triggering event, but self-reporting is just not sufficient. If you’re fine for the first hour of a 3-hour flight, and then go berserk half-way through for whatever reason, you have a tragedy and the murder of 149 innocent people.