The door being blocked additionally by a food cart may be an additional security step. Some airlines treat having the flight crew needing a bathroom break very

The door being blocked additionally by a food cart may be an additional security step. Some airlines treat having the flight crew needing a bathroom break very seriously when the cockpit has to be opened in flight (ex sending passengers back to seats if they try to go to the front bathrooms, closing curtains, lead staff up front on standby, etc). Here's the cockpit locking system on Airbuses, for what it's worth as well: https://www.youtube.com/watch?v=ROIH3KCEIvs https://www.youtube.com/watch?v=ROIH3KCEIvs There is a button that sounds a 'request' chime, and a code that when entered starts a timer and alarm that once stops, releases the door momentarily for an emergency entry. The crew inside can still disable that unlock, if they are conscious (and this is some kind of attempted hijacking with knowledge of the code).