Agree. As part of our security procedures, the lavs will often be locked to clear the area near the cockpit. Without further detail, I'd submit to you that overriding a locked lav door might bring unwanted attention upon yourself.

It's not.

I'm also fairly certain that when the seatbelt sign is on, the lav occupied lights will illuminate. Therefore, you might see the lav occupied light on when: A. Flight attendants have locked it as part of a security procedure. B. Flight attendants have locked it as part of takeoff/landing procedure. C. Seat belt sign is on. D. Lav is actually occupied. E. Lav is inop and locked per a maintenance procedure.