Air shafts imoThere is a reason the shafts were built. And there must be a reason their existence was hidden.
the reason to hide them so as not to give any potential tomb robbers clues as to the location of the chamber and at the same time to not give them any air when they get inside
Its fairly obvious that the pyramids were built from the ground up. I don't think anyone stable has ever refuted that


so the chamber was finished earlier than the shafts were sealed at the upper ends. all that then remained was for them to be sealed at the lower ends when the structure was complete and the chamber used for whatever it was designed for
the simplest answer is often the correct one.
Gantenbrink may simply be wasting his time.
on the other hand
it may be possible that there is a smaller chamber further along the passage behind the metal plate and that it was sealed off as the building was constructed and whatever secret thing was hidden higher up neccesitating the shaft to continue to the outside for ventilation for that area.
withhout dismantling the pyramid i doubt anyones going to find out. its very difficult to get a robot with cutting equipment to open the door from the outside
thats if the E.A.C would even allow it anyway