I personally don't know, just am asking questions.
I don't know how things are separated and isolated on that a/c.
Otoh, a fight, leading to a zoom climb to FL450 and then to a stall and fall to recovery is certainly possible, if that reported flight data is true.
It's all just speculation.
In reference to the passengers, now we need to go back to your term, deploy. Masks will deploy automatically at a cabin pressure altitude of 14,000 feet or if manually deployed by the cockpit crew.
Don’t assume the airplane will stall at Flight Level 450. I got into it with another Freeper on that topic. I’ve taken airplanes above their service ceiling on a number of occasions. The retired captain that called Rush confirmed that a B777 can sustain flight at FL450. A service ceiling is defined as the highest altitude where an aircraft can maintain a fifty foot per minute climb.
And like you, I don’t put complete faith in the FL450 number until we know more about the source.