BEA's reasoning in its commentary posted by GlueBall is viable as far as it goes.
But there is one giant piece of data missing from the report that left this opening for BEA; namely, a recreation of the accident scenario up to the first rudder pedal movement in the second 747 wake encounter-- definitely lets not do more than one.
If Airbus is that confident of its engineering, why did it not arrange for such a test?