Frankly Hotdog whether it was actually authorised or not is not really the point. The captain takes ulitmate responsibilty. Management are always going to cover themselves. They are unlikely to admit to it being authorised and therefore if they don't admit to it then it wasn't, unless the captain has it in writing.
With the public having just seen a 777 crashing in the undershoot at Heathrow it was very tactless to do a low pass which would be photographed. With the Heathrow accident it would also be very likely that management would deny any authorisation having been granted, especially after the video was posted on youtube (now removed - probably because of public perception after the Heathrow accident).