PJ2,
Thank you for the interesting article on C* control.
From the small amount of information that BEA released, it still seems likely to me that difficulty in controlling the lateral channel was at the root of the loss of control in pitch.
If lateral control was difficult enough, that could take all the PF's attention.
I wounder if it is practical to split duties between pitch and roll channels between the two seats as an emergency means of control in a high workload situation? Very un-Airbus of course.
Your stick force diagram posted a couple of days ago showed much higher forces for the lateral channel of control than the A320 information I re-posted from an old 2004 posting on the subject. The higher the stick force gradient, the greater the lateral control difficulty with a "wing heavy" condition.