even a deranged crew member , German Wings, led to the loss of the aircraft and all on board. Why take the risk,
An odd example when you consider that it was strict flight deck security that created the conditions for that accident.
The 'different customer base' point is not just about the reduced likelihood of unlawful interference happening in the first place: it's also that 200 squaddies are extremely unlikely to sit there doing nothing while their flight is unlawfully interfered with!
Personally I think the open cockpit on military AT is a wonderful thing; it is an example of implicit trust, which is good for cohesion between arms and services, and it enables flight deck visits which give servicemen a little bit of insight into why the Air Force is the way it is.