What a bizarre event. The headlines and murder investigation would imply that the aircraft was deliberately manoeuvred to strike the pedestrian, whether airborne or landing. However, reading the articles it seems that the aircraft was taxying after landing. Now, if the man intended to remonstrate with the crew and stepped into the taxyway to try to force the gyrocopter to stop or entered the rotor disk without clearance or an understanding of the dangers, then the accident would be his own doing. I find it very hard to imagine that any pilot (no matter how 'extremist' his views) would deliberately attempt to kill a person by running them down with his aircraft.
This is of course my own speculation. I will be very interested to see how this investigation continues. The above being an accident would not excuse the alleged behaviour of the crew in the previous weeks. If indeed he was using the aircraft to illegally low fly with the intention of harassing people on the ground, I hope the CAA would take firm action.