EU re-writing - or has re-written ? - regulation.
Because of the differing interpretations that airlines have been using for "exceptional circumstances" and the many complaints this has engendered, the Brussels intelligentsia has now clearly stated that aircraft faults/lack of crew etc which are completely controlled by the airline
( whether they can do anything about them or not ) are absolutely not "exceptional circumstances" and compensation is due.
Believe this was in "Der Spiegel" during the past couple of months..
Don't know if their saying it makes any difference or if they have to actually get the regulation re-written.
I would think the OP has a cast-iron case if he wishes to pursue it.