My Two Pence worth,
My understanding is that NO ONE is allowed on the jumpseat unless they are CAA/DOT in the course of their duties or operational crew i.e. Training Capt on a Line Check. Even Company personnel are banned if they are not ON DUTY.
So if you're off duty you're more likely to hi-jack/crash the aircraft rather than when you're on duty and ALREADY at the controls.. that makes it all clear then.
As someone said, they have taken over the asylum
