The First Officer who was the flying pilot on American Airlines flight 755 from Paris to Philadelphia on November 29th, had a seizure that stiffened his legs and back, jamming his feet under the rudder pedals on short final approach. The captain immediately took over flying duties and there was no loss of aircraft control.
The relief pilot who was required to be on the flight deck during landing was able to remove the unconscious pilot from the seat with the help of the purser. The relief pilot occupied the seat for a normal landing and taxi to the gate.
Long international flights are the safest right now due to extra pilots required to be on the flight deck during critical phases of flight that include the takeoff, initial climb, final descent, and landing. This extra pilot requirement does not currently exist for domestic flights and short international flights. However, having that extra layer of safety will not matter if this scenario happens again with involuntary flight control inputs. No number of pilots on the flight deck will be able to respond in time.