Originally Posted by
fastjet45
As others have said I am not convinced two in the cockpit at all times will ultimately be a solution. Using that theory it means bringing in a cabin crew member while one pilot visits the bathroom who will most likely have no idea how to fly an aircraft, all it would take is for the remaining handling pilot to quickly shut off the engines and or electrics and announce you have control while the person who left the flight is locked out.
All security is a tradeoff. The locking doors, for example, were a tradeoff between crazy pilots breaking into the cockpit to crash the plane and crazy pilots already in the cockpit deciding to crash the plane; the expectation being that the former was far more likely than the latter. There's no 'solution', only ways to reduce the risk of something bad happening.
Having two people in the cockpit at all times further reduces that risk, but clearly won't eliminate it. Nothing can remove all risk at all times.