Thus, more evidence is required to ground an airplane (that has, after all, gone through the certification process), than two crashes.
As someone pointed out in this thread, there were three B767 hull losses between September and November 2001, but two of those were caused by 9/11 terrorists and don't tell you much about the airworthiness of the aircraft.
The fundamental question is this: should the plane have been grounded immediately after the second crash? Many here seem to think that yes, obviously. I think that no, one unexplained crash of a certified plane does not warrant grounding. Once details and circumstances emerge that are indicative of some fundamental design flaw, or multiple unexplained crashes (as with the comet), of course ground it.
Is that a substantive disagreement, or "pedantry"?