Athonite
Having bumbled through your post (and its disjointed words and spellings), I think I agree with you in part. There have been a number of "Gentlemans' Fast Jet Flying Clubs" that have come a cropper due to the inexperience or lack of ability of some pilots; but I think in this case we can safely say that flying a number of hours on Tucanos and Hawks has given this particular pilot a large amount of experience to draw upon for flying a Gnat. The Display Authorisation (DA) process is pretty rigourous to get through and so I would offer that he should have the skill to complete the activity as planned.
However, it is when it goes 'unplanned' that the inexperienced, or those with lesser capacity, come a cropper. This is where I agree with you about having a demonstrable and significant amount of experience
on type (or very similar) before the grant of a DA in a fast jet like this. However, all said, even Chuck Yeager can have a bad day (and he did in a F-104!
).
LJ