@NigelOnDraft
In operator I work for, and I presume most, remember when the situation is clearly catastrophic / dire, the CC can evacuate on their own initiative.
When I worked as CC with Northwest many moons ago, we were to chant "brace for impact" in unison until the plan landed (or worse). Upon the AC's stopping, we checked our watches. If the flight deck didn't get on the PA to say "stay seated" or something similar (I don't recall the exact wording) or to say "Evacuate the airplane", either within 20 seconds (don't recall the exact time period), CC was to evacuate the AC. CC had the right to evacuate on its own if doing so was obvious, but the above was the procedure.
Of course in Asian 214's case, no one had time to prepare to brace for impact.