I'm surprised the pilots didn't go illegal at the 8 hour point after pushback. By my quick calculations, it must have been their first flight of the day. Otherwise, they would have exceeded 8 hours before takeoff.
One reason the flight crew may not have been in any particular hurry is that the Captain was earning at least $181 per hour while parked waiting for de-icing and the First Officer was probably earning at least $120 per hour.
I understand that icing causes delays, especially at southern airports which don't experience snow and ice very often.
But 9+ hours? Someone dropped the ball. That's outrageous.