My understanding is that East Coast have a bevy of on-call managers, whose responsibility it is to ensure that resources (including themselves, if necessary) are in place to deal with issues arising from late running trains after network disruption. Whatever the 'normal' staffing level is for Kings Cross at midnight, it will be inadequate to deal with requests for taxis, hotels, onward travel advice, locking up of sets before them going off to the depot and passenger assistance. The real question then, is whether EC made any effort to supplement the night staff and if not, why not?
I would assume that extyra staff were there otherwise there would have been far more reports of stranded travellers unable to gain assistance on arrival.
I still believe that, despite extra staff, the assistance list was overlooked or misread, and that we will never eliminate this sor tof thing happening entirely.