Most Airlines have fully trained OPERATIONS staff that deal with these type of things and instruct the crew as to what the company want you to do. They know lots of things I don't such as overflight charges, landing and parking charges, interline connections, Engineering rotations, fuel prices at each port, medical facilities, staff availability, hotel availability, catering availability , blah blah blah. IT'S THEIR JOB TO KNOW, not mine.
If the airport is serviceable ( lights on, aids on, ATC available, Wx ok ) then if my company make the decision to dispatch the a/c ( even after I remind them about a curfew ) then it's their call.
My control as Captain starts at doors closed and pertains to the continued safe operation of my Aircraft. Busting an airport curfew doesn't constitute a safety hazzard of any sort. It may be wrong and indeed illegal but...................that's another story for the lawyers and ops people to sort out.