Usually past practices of other Airports around the globe that operate to similar curfews was to use a "common sense approach" in times of adverse weather and provide operators dispensations to depart during times of curfew to clear the backlog of flights.
Sadly though, Sydney Airport does not and will not contemplate operating with this flexibility. (Probably mainly due to misinformed Government numb nuts intervening and trying to kick political goals in their electorates.)
As mentioned before, all this just adds to Australia continuing down that slope of becoming more and more a Global Joke in the eyes of the rest of the world.
Sydney airport continues to consolidate these views.
