"Actually you can taxi towards someone and the person would still be hit by the rear pointing propeller as the width of the prop is wider than the gyrocopters fuselage."
Though with the wheel track and tailplane span, it would be difficult for a pilot to engineer a deliberate prop strike.
I wasn't there, I know nothing of the circumstances, but in my experience, the level of aggression, intimidation and violence shown by vehicle-mounted hunt followers and supporters towards those they perceive as being 'Antis' is astonishing, and quite the equal of anything that we see from the 'Antis' themselves.
I wonder whether the victim didn't simply approach the aircraft with his 'blood up', looking for a confrontation, and then tripped over the landing gear straight into the prop. It certainly seems more likely than 'murder'.