why make that change if they did not mean something by it?
There were substantive changes to that paragraph. It is entirely possible that deletion of the words 'througout the demonstration' was thought to be editorial, non-substantive. In any case, those changes had nothing to do with AF447.
Perhaps the condition that all three AoA values are NCD while the airplane is in flight should be considered a failure of the stall warning system:
Originally Posted by AC 25-7C
228. Design and Function Of Artificial Stall Warning and Identification Systems.
d. Indicating and Warning Devices.
(2) Warning that the associated systems for operating the stall warning or stall identification devices has failed should be provided. As far as is practicable, this warning should cover all system failure modes.