However, why would Airbus programme the systems to abandon functions and leave the stabiliser control surfaces in such an extreme setting.
Don't have an opinion on that, but one needs to consider the failure modes that "fixing" such a problem could induce. For the aircraft to end up in such a significant out of trim situation to begin with, something must have gone badly wrong that the computers have not picked up on. We wouldn't want a sick computer, when it finally realizes it has lost situational awareness, start guessing as to what might wrong and take actions based on those guesses.