So the question becomes what is different about the bus' reaction to discrepant a/s? Are we certain that three pitots failed on 447? No.
What is AB's plan for unreliable air speed driven a/p? I'm reading about pitot/a/p problems in Boeing, in climb, and single failure as well.
If the AD calls for r/r of two pitots only, and AB believes all three failed on 447, you see the problem? Something doesn't fit.