IŽd love some reactions to this hypothetical but valid question. This is what could have happened if not FO on this flight had succeeded in getting the captain out of the cockpit and locked the door.
What do you do? Door to cabin is closed. Your colleague starts messing with the controls in a dangerous way and is obviously losing it very, very rapidly? Putting plane and passengers at an obvious risc. Flying all over the place. He is "incomunicado"!
Crash axe?