Flight SEA-PDX on Feb 9 in the morning was delayed by over 2 hrs because the inbound ex PDX was iced up overnight - Captain eventually said they couldn't get the door open as it was coated in ice. They switched aircraft and then operated the flight.

So, is it reasonable for UA to claim is was a weather caused delay? I don't believe so as this weather was forecast at least a day in advance and if they shut down the aircraft the preceding evening with due regard for what would happen overnight, the flight should have operated as planned.