Yes, that's what I was thinking too ! I mean, the 78 bogie wagons in this incident, is quite a length. Applying, say one handbrake in every five, for example, would surely take almost two hours ?
I know it's not the case here, but Imagine too, if all the locomotives had been shut down, while the train was stabled overnight, then the air pressure throughout the train would have dropped considerably and may take well over an hour to build back up again, once the loco's were re-started, I would have thought ?
(I heard of one case, from a friend on holiday in Canada, that he observed a freight train there, take most of the day to build up sufficient pressure)