First, regarding livestock ... helicopters are used to drive herd animals, so both bovine and equine stock will indeed respond to a rotorcraft. That includes horses, burros and cows ...
http://www.fund4horses.org/pdf/Helic...alJune2007.pdf
Second, the issue of the pilot's behavior or the pedestrian's during events prior to the time proximate the encounter on the ramp are irrelevant from an aviation standpoint, although they may have a bearing on judicial proceedings and decisions.
Third, it would seem that the issue in question is why the pilot in command did not adhere to UK CAP 768 Ch 10 Annex 1 regarding ground operations and ramp safety. There really are only two alternatives: 1. the pilot operated in an unsafe manner and collided with the victim or 2. the pilot intentionally used the aircraft to collide with the victim. Since the authorities have responded with a murder investigation, it seems that they believe there is sufficient evidence for alternative 2.
IMO the gyro plane is one way that a larger number of private individuals can become members of the aviation family. It is unfortunate when some choose to behave irresponsibly or criminally and cast a bad light on the rotorcraft community. It would be a shame if this event led to increased restrictions on the UK rotor sport community...