[abaillargeon]

Correct, there was probably a significant amount of simulator testing. Keep in mind that these kinds of simulators use real hardware and the avionics are being given inputs just like in the aircraft (i.e. the GPS antenna is simulated, but GPS inputs and uncertainty propagate through the system just like in the actual aircraft)

Most likely there is a test mode that raises the altitude floor/projected flight path at which it takes over. You could then perform the level-off at a safer altitude.