Lu - I have great respect for the seriousness and content of your posts and the rigorous standards you apply. In this case, however, your argument seems a bit circular. OR maybe I need a nap.
If I understand your post, you say: evidently the a300 did not / does not have an SCAS package, but IF IT DID, then it would have been overloaded by the sudden burst of exceptional data.
As long as we're hypothesizing a monitor / control system to replace the one that isn't there, why not hypothesize one that works?
I know a thing or two about computers, and betcha we can whittle up a design for an ultrareliable one of them that will process anything you can throw at it, speed and complexity-wise, in the way of airdata and derivative rules.
Possibly - as Belgique and others, I believe, have remarked, the sensor data resources integrated into the existing A300 airframe are too filtered and / or slow to provide adequate control data response for this new task. If so, then maybe one would have to tap a couple more holes to augment the sensor set.
Perhaps the way to make entire generations of aircraft safer is to require some standardized air-data sensors and processing tools as a generic airframe component, part of the backbone, developed to a common performance standard. That might make for economies of scale, concentration of greater economic effort in quality development in this complex and expensive part of airframe design, and might pave the way for mid-life fleet upgrades by replacement of the generic portion from time to time - feasible if it maintains a standardized interface to the airframe and proprietary stuff up front.