medhead, absolutely.
While it is probably the case (without looking up weather bureau records) that on Sunday night 5 June 2016 the situation was more 'severe' (because it had gone on for longer, and there was 150mm of rain in 30 hours at SYD) than on the previous occasions I highlighted in the report tabled in Parliament (go back a few posts in this thread), on the latter occasion when there was a 'normal' government functioning, two requests were NOT approved.
Melburnian 1 curfew dispensation has always been and will continue to be very rare. There have been much more severe weather which has brought Sydney to a complete standstill from 5:30 until close to curfew. On one occasion 6 or so years ago there was lines of aircraft who had taxied stopped on taxiways unable to depart due to storms sitting over the airfield. No dispensations were granted on this evening and it is my experience that a dispensation is very much a one off and applied for a significant reason.
Last night, it appears ALL requests were approved although to know that for sure we will have to wait until the next report is tabled in Federal Parliament. However I am unsure why they were approved (if in fact they were).
It is more likely that no dispensations were applied for and the airlines operated within the legislation of the curfew period. You stated that the last depart was at 2319, that is not a long time at all if the crew were trying to depart on the duty runway prior to curfew, realised that they were not going to make it, pushed back and received a taxi clearance prior to 2300 and then sat at either a holding point or on a taxiway to redo their performance figures etc and assess the conditions for departure on RWY 16R. The legislation is very clear that provided an aircraft is in receipt of a taxi clearance prior to 2300 they can depart from RWY16R at 0559 if they have had to wait that long.