The other issue BA was touting was that crew were out of position due to the disruption. This, of course, was in some cases absolutely valid. However, it seems that BA's internal systems were as much messed up as its customer-facing systems. Speaking to the crew on my flight yesterday, when they reported for duty at LHR that morning, they were told that they weren't expected since BA's systems thought they were still stuck in Dublin! They said that even after they had confirmed they were there and had been reallocated to the flight, the systems dropped them from operating my flight again!
In my view this is a bigger screw-up than the IT fiasco earlier this year. If BA had been prepared, had contingency plans in place, had decent stress-tested IT systems, the impact of a tiny amount of snow and cold weather should have been a fraction of what it was.