I see many references to an "active" runway and I wonder how it could be "active" with people standing on it and other airplanes lining the sides of it. Five minutes after the incident the Air Boss informs the RC pilot that the FS had landed. There must have been another runway there that was used.
If I was the RC pilot I don't think that I would expect a FS plane to buzz the runway at what, a hundred feet".
While pedestrians have the right of way, if one runs out in the street from behind a parked van and gets hit by a car, is the driver of the car at fault?
If I was the RC pilot I would have to trust that the people running the show knew what they were doing and when I was invited to demonstrate my plane it was safe to do so.
My feeling is that the RC pilot was the victim of a reckless FS pilot.