Obviously too early to establish the facts yet, but I hope EK don't rush to apportion blame before assessing all the evidence. Especially bearing in mind the press are reporting that the crew took the turn too late... According to expert passengers anyway.
The thing is that snow covered taxiways and taxiway edges are very difficult to identify when using the gear cameras. The quality isn't quite high enough definition, and it is even apparent in bright sunlight when the taxiway Tarmac and the non-load-bearing part of the apron are similar colours and textures. It's difficult to identify both the centreline and the edge markings. Quite often the cleared snow is dumped across the edge lighting which then becomes buried and useless.
I really hope the Company take a common-sense approach to this incident if this is indeed what has happened. It's extremely unusual circumstances for crews who are mostly inexperienced in these sort of conditions. The extremely tight taxiways at UK regional airports don't help either, especially on such a long bird as the 300ER.