Mr O.
Ideally, roll control being maintained would mean to me the PF remained wings level when that was the called for flight regime: maintain course and speed to get to next navigation point.
You are probably right, but the BEA reports roll excursions. One need not fault the attitude indicating system for that ... other explanations have been offered that do not point to a failure, for which various data to date have lacked one labeled "inertial reference/AI" failure.