Too many times the pushback has failed to release my 'Nose Wheel Steering'. It's totally unreliable!
GSX is not releasing or locking anything, especially on the FS Labs airplane, which has a custom nose wheel system.
The only thing GSX does, is to set a variable telling the airplane when it wants the bypass pin to be released, so it can control it by itself during the actual pushback, and set it again when pushback ends, to tell the airplane to claim back control of the nose wheel steering so, it's up to the airplane to react to this variable and reinstate control of the NWS to itself.