I'd suggest it's more about French face-saving. Maybe we'll hear some details of the arguments in due course, but it seems a strange. IIRC the story is that a bit fell of a CO aircraft, wasn't cleared off the runway before the Concorde began its takeoff roll, and then caused the fatal puncture to the fuel tank. But bits do fall of aircraft now and again, and if the finger of blame points anywhere here (and we don't just say it was a tragic lining up of holes) then wouldn't the airport be first in line for not clearing the runway?