A few considerations to take into account (and there are probably others one could dream up) ..
(a) depressurisation - without dropdown masks (and no oxygen gives the same result) the normal certification limit is FL250 and, if the memory serves, a maximum 4 minutes to get down to 10,000ft.
(b) base MEL consideration would consider continuing at cruise
(c) smoke and fire drills are a definite consideration
Perhaps they might have been after an answer along the lines of ..
(a) if fuel critical, stay high on a risk management consideration
(b) otherwise descend to FL250 and continue
(c) consider diverting to nearest alternate due loss of crew smoke protection but balance an assessment of relative risks overall