Allowed to land the plane in an emergency... why not ? that means there is no more pilots in the flightdeck... Therefore...Cabin crew or else what is the difference ?
What should really be implemented is an emergency FPL, leading to a suitable runway, all automated, speed managed, only thing to do would be to lower the gear and flaps, nothing else and noone sitting in the pilot seats. Than after landing emergency shutdown drill and evac.. Who else could do that besides a cabin crew ?
By the way, if the Commander and the first officer are dead/unavailable/etc... the new commander is the purser, so what ?