Jay
Fortunately in the U.K. To find someone guilty of a criminal offence you have to prove intent or negligence and a simple mistake is not negligence as the pilot did not eject from the aircraft and attempted to recover the situation this would indicate a mistake on entry to the loop rather than intentional or wreckless negligence. It should also be remembered that the AAIB report can't under international law be used to prosecute the pilot and the police have to collect their own evidence, another thing that has to be considered is if prosecution is in the public interest, the huge costs involved in bringing the case and the questionable chance of success along with the fact the pilot clearly did not intend to crash the aircraft and is not likely to re-offend are all going to be factors the CPS will consider before bringing this to court.
It must also be remembered that some of the victims deliberately placed themselfs in a more hazardous position to watch the show for free and so presumably excepted the additional risk, I do feel very sorry for those victims who just happened to be passing by in the course of normal daily life unconnected with the airshow who could not have known the risks posed by the show and so were not in a position to deicide to or not to take the risk of being in the area at the time.