David Horn...
It's interesting that Airbus advice is to turn off two ADRs, which immediately adds to confusion in the flight deck with only one air data reference available.
But that is preferable to seeing increasing nose-down pitch which you cannot correct in Normal Law...
Is there any reason why the FACs couldn't be switched off instead to drop the aircraft into alternate law?
Short answer: A330/340 do not have FACs.
Thinking of the A320....?
1. The ADR pb's are located together on the overhead panel, directly above the captain's head, whereas the FAC pb's are one either side of the same panel. Much easier and quicker to use the ADR pb's.
2. Switching off both FACs has more effect on the rudder - it leads to Mechanical Yaw instead of ALT.