Its a fascinating piece of security theater though, that staff at the aircraft door have been trained to deny entry to someone already in the aerobridge who has shown a boarding pass. Apparently criminals can now teleport themselves into the aerobridge without going through the gate at the start of the aerobridge...
Maybe whomever trained them in this could roll out some Priority Boarding training to Qantas staff?
Maybe too hard for QF IT to design a timer in the app to keep boarding passes valid 30-45 minutes past planned departure time to allow things like this to not cause further delays?