I'll pre-empt this by saying I know bugger all about bang seats but it was my understanding that once the seat leaves it's rail the deployment of drogues/parachutes and seat separation etc. is all automated and "foolproof".
If that is the case then how could MB claim there's no failure in the seat? Reports seem to say there was no seat separation or drogue/parachute deployment. I can understand how they might be able to "get away" with saying it's not a fault of the seat that fired the it but after it's off the rail surely it's all MB...