I would not think flying to follow a hunt, for example to make sure it is a real dummy hunt is in itself illegal, as long as the 500 ft rule is obeyed, just like it is not illegal for a dummy hunt to take place providing the rules are obeyed.
If the Gyro was purposely trying to annoy the people involved in the hunt this would be different, but either way all this talk of the hunt is merely creating the framework for whatever happened at the airfield.
So the question remains, how is it possible for somebody to walk into a blade and be killed.
3 options have been provided:
1. stumbled over a wheel when approaching the craft (accident)
2. unexpected weathercocking of the craft (accident)
3. purpose pointing the blades towards the victim (murder or protection reflex in case the approach of the victim was considered to be threatening)
The aircraft had completed refueling. Unless the fuel is right next to the hangar where it is based and is due to be put away, it would be logical for the engine to be restarted.
Perhaps the hunt issue is the key for the investigation and charge. This is a highly sensitive issue and the prosecution will not want to be seen taking sides, in which case a court case and decision by the judge (either way) will prevent the prosecution being seen to be taking sides.