As you say this is all speculation since we dont know the remaining fuel but (and I know I am sticking my neck out here) perhaps, from a strictly decision making point of view, there might be some similarities between this accident and the BY one at GRO where the aicraft exited the side of the runway after an unusual arrival following an approach in not dissimilar weather.
Concerning CAT !/III surely from a pure systems point of view there is no reason why the aircraft could not have done an autoland (yes I know there are crosswind limits, weather limits etc) but if you really running low on fuel it might be better to autoland.
Pith helmet suitably donned!