Sloppy joe
Answer to your query
LOCK position :
Once the button has been moved to this position, the door is locked ; emergency access, the buzzer, and the keypad are #inhibited# for a preselected time (5 to 20 min).
This may explain why the cvr seemed to indicate that the Capt did not use the emergency access code. Since it could only be confirmed by a recording of the beeps of the keyboard or the buzzer going off in the flight deck. If they were inhibited, no noise was created.