I think that mainly he just didn't watch the speedo and let the speed bleed off, and eventually stalled.
He should have gone to full power, initially without climbing; he had plenty of height (50-100ft?).
As regards flying to busy events, nobody is perfect and that is why I won't fly to some of these. I didn't fly to Sywell (with their crazy "non radio holding patterns on base leg") last year, and when I went this year I departed at the earliest possible instant from my base, to get there as early as possible, to minimise the chance of hitting somebody. I go to Friedrichshafen but I go IFR which gives one some level of protection from crazy pilots. I would not fly to a big VFR-only event in France; I've already had two cases of being cleared to join base at exactly the same time a French pilot was cleared (in French) to join on the opposite base (LFAT, 2002 & 2011). At home, when I hear there are 6 or 7 in the circuit and 3 more in the overhead (each one uselessly looking for the other 2), I sod off and come back 20 mins later. Only Roush could have made that decision for himself. I think most pilots will fly to busy events (self evidently true
) without worrying about it. One could argue that if you cannot do a go-around (from any position) then you should not be flying, especially a jet.