THR RED ACC, brother!!
What if the captain bangs on the door to let him in but the copilot claims he's having psychotic episode!! What to do?? Legally she's obliged to open the door!
Think that's far fetched? I remember a incident on a jet blue flight where the captain developed such an episode!! Granted, the second person on the flight deck happened to be an off duty pilot, but what if there was not an off duty pilot onboard?
Wow, what choice would. A CA face, the copilot which a strange look on his face claiming the captain is crazy or the copilot is crazy. Just saying!!