If the brake pedal can move toward the rear of the car. The pedal is not stopping the mc from returning all the way.
There is no return spring on the pedal so the internal springs in the MC are the only thing returning the pedal. If the weight of the pedal is causing the MC to be pressurizing the system there is a much bigger issue with the MC.
Unless he's checked the wheels for free movement when he pulls the pedal back, he doesn't know that. It makes ZERO sense for him to not try it. It's either two or four nuts is all he has to loosen. Five minutes.