The FAA's primary mission is to improve flying safety, not necessarily making someone's life more miserable, although the lines can get blurred at times.
In the case being discussed, the RC pilot chose to disregard AMA as well as FAA guidelines regarding RC flying in relation to real aircraft. The pilot of the Acrosport also showed questionable judgment in doing his low approach, but it is something seen at nearly every fly in, without consequence.
All of the blather about the "airboss" means nothing to full scale pilots, who know that two way radio communication is not required at uncontrolled fields. A guy with a handheld, which have limited range even under the best of circumstances, is not an FAA controller. Was there adequate notification of all of the pilots that RC models would be on the runway, and that people would be standing on or adjacent to the active runway? Was there a NOTAM issued, and were all of the tenants and all of the pilots with permission to land at the private airport also notified of this hazard? Did the flyers say: use caution, model aircraft will be on the active runway during the flyin?
Also, A plane attempting a full stop landing could also easily have met the same fate, since the RC demo appeared to be at or close to midfield. The issue of the low pass is less when this is taken into consideration. The RC demo could easily have occurred at any number of places a lot safer than over an active runway, or with a crowd close by, which also goes against the basic safety tenets of the AMA.
A true airshow, with performers, requires reams of paperwork, land plats, 500 foot dead lines for safety, fencing, coordination with fire rescue, etc, and takes months to plan. The FSDO almost always has someone in attendance at these events.
If you meant fly ins and not airshows, I do not think there are as many, if not any, restrictions.
I would like to see the final results of the investigation- would they be available under the Freedom of Information Act to any interested party?