Surely it could do that perfectly safely without either as long as there were no obstacles in the way!
I concur with Machinbird. The demonstration as planned: a fly-past at Valphamax and alpha-max, therefore with thrust control the only means for controlling the height of the flight path, could not be done safely at 100 ft above terrain, let alone 40 ft. In any case it could not have been done with the level of safety required for a passenger-carrying flight.
Just imagine: To achieve alpha-max you have to pull the sidestick to the rear stop and keep it there. To maintain level flight at alpha-max you have to slow down to Valphamax. The only way to 'pull up' in that situation is to increase thrust to accelerate to a speed greater than Valphamax.