The problem is trying to ascertain when the pilot knew he had a problem that needed resolving.
If he knew at the apex that there was a problem and he didn't take the appropriate action ie emergency measures this could be deemed negligence but maybe he was unaware at the time due other factors such as altimeter mis-reading the height, the engine not having the thrust he thought he had etc and it wasn't till he was half way down the loop or near the bottom that he had a problem.
Does any ex hunter pilot know what the 'emergency' plan would be then... eject and leave the aircraft to its own devices or try and plant it somewhere safer and maybe kill yourself trying..