I suspect that answer here, if there ever could be a "correct" answer to such a question, lies in the area of probabilities much like the basis for the MEL.
Along the lines of what is the probability of losing all crew O2 and then the on the same flight what is the probabilty of suffering a depressurisation? And so I believe such questions are merely exploratory to get a feel for how the person thinks on their feet.
Some will be quite happy with placing pax 02 bottles on F/D and making a judgement on the likliehood of a smoke problem etc whilst others will not even contemplate it and commence immediate descent and/or diversion. Even the questioners cannot know the exact answer to this question,; only what their personal take on it would be unless their ops manual specifically caters for such a scenario and I am not aware of any regulatory authorities who mandate that procedures for such should be developed.
It is simply interesting to question and discuss amongst peers but it is never intended to produce a definitive answer.
Just my tuppence worth.