Still doesnt seem right to despatch with a no go item, knowing it will clear
Assuming the engineer wouldn't dispatch it, he would have got in the flight deck for a check swing and as soon as the a/c had gotten back far enough from the stand for the defect to clear would have realised it was a stand problem and released the a/c.
It would be a good idea, spanners, if you write to the airport authority and to your technical/quality department to advise that this stand/aircraft combination causes compass errors. Could save several hours delay one day if this info is circulated.