Based on the presented facts, a total overreaction. Locked doors cannot come open in flight. Deploy the masks just in case??
I've always been intrigued about this "announcing" the emergency descent. What is the point, apart from to your FO? What are the pax going to do apart from cr@p themselves (not having heard the term before)? What are the FAs going to do? Jump up and run around like headless chooks or simply grab a spare mask when/if one appears?
Given the manoeuvre should be smooth and be all over in a few minutes, surely the popping out of the masks (if indeed they do pop) will be enough "advice" to indicate to the masses in the cabin what is occurring and to do?