While it is physically possible to move a jetway with the aircraft door open, it is airline procedures for obvious safety reasons to insure the cabin doors are not opened until jetways is fly docked,. Likewise the jetway must not be retracted until the cabin door is closed. These are sop.
For certain regional jets that have folding stairs .mechanically linked to the door, they must be opened prior to the jetway docking, and closed after jetway is retracted. This is supervised procedure and a safety risk.
GSX is working correctly.
It might be a consideration for a future enhancment to have this configurable by aircraft?
