This pilot almost got away with his manoeuvre. If he'd had another couple of hundred feet, it would have just been another 'interesting' clip on youtube. There are many clips there of near misses (and non misses) with the terra firma, usually by well trained military pilots flying a variety of modern fighters. It can happen to the best of pilots in the best aircraft. And it regularly does....
If he'd smacked it into some farmland, there would have been a great deal less fuss, but it would have been the same accident as far as the nuts and bolts of what caused it are concerned. I suspect calls for 'something to be done' would be just as absent as they were after the recent Gnat accident.
Heaven forbid that the findings of the AAIB should be anticipated, but I'd happily bet my next months wages that this was just exactly what it appears to be.
Not the first by a long way, or the last.
Barring the odd unfortunate occurrence, like this one, the 'system' has done a damn good job of protecting those near to, and attending, Airshows for decades. Quite a few decades...Has everything to be zero risk?
Precisely nothing needs to be done, apart from the CAA resisting the urge to kneejerk the very much attended and enjoyed UK Airshow scene into another 'elf 'n safety, hard hat zone.