Pitch Control Power Design
For commercial aircraft that have the conventional arrangement of an all moving horizontal tail (stabilizer) and attached elevator surfaces, demonstration of sufficient control power for continued safe flight and landing with the stabilizer stuck at any "normally encountered position" is a requirement. There may not be sufficient pitch control authority in the elevators alone in the event of a stabilizer that is stuck in a position that is grossly out of trim.
For this reason, monitors to detect uncommanded stabilizer motion and provide rapid automatic shutdown of power to the stabilizer trim motors are common. Another fallout of this is that failure combinations that disable the stabilizer and significantly reduce elevator control authority must be shown to be extremely improbable.
It seems to me that the scenario described is more a matter of whether or not the airplane is left with sufficient control power to continue with safe flight and landing, not a matter of pilot ability to handle airplane path control. Of course, procedural limitations on thrust and flap that impart significant pitching moments must be honored.