Well from what I have read on this thread there seems considerable 'doubt' as to exactly what sort of military flying qualifications the pilot had.
......not helped by the curious evasiveness of the group's website around the subject which I also looked at.
That is why the matter is being raised.
I myself was aware that there were civilian Gnats flying but I had never guessed there was a team flying formation display aerobatics in them which personally I would have thought is the field of full time RAF pilots only.