Not a "shoot down" as such, I gave them up in October 2002, but the reason we have CHIRP, MORs, etc is because things don't always turn out as "expected".
Ignorance is no excuse, agreed.
However,
With the cutover to the new NOTAM systems there were problems. Fact. Acknowledged by AIS, NATS and CAA.
Someone diligently relying on "the system" to give them the information they required could easily have been mislead (or worse, completely uninformed) about the air-display times and/or location.
To expect pilots, no matter how diligent, to telephone and check NOTAMs after they have pre-briefed from the State's AIS site is näive and not "real world".
The fault, if any, is with the pilot for not talking to 124.6 and checking the NOTAMS enroute once the decision to re-route was made.
If there were no issues with the briefing system, why have NATS spent >£100K and 8 months fixing it?