A and C,
The difficulty appears to be with the ability of the elevator to control pitch - nose up, before the procedure can be used.
Larger tail area - trim, same elevator, changes in aerodynamics, hydraulic jack stall. Perhaps small changes, but incrementally eroding the margin for recovery.
Inaccurate simulation, false assumptions based on previous, smaller aircraft.
futurama, ‘zero accidents’ does not affect the inherent risk of system failure - outcome bias.
Never a zero chance of anything, particularly in aviation.