It could, perhaps, start by not having a display line which puts energy vectors along a busy public road.
Exactly.
With an option always being to stop traffic on the vulnerable portion of the road for the few minutes where there would be a risk from the one or two aircraft considered to have enough energy to create risk....
Or, display the aircraft with maneuvers limited to those which do not create the vectors to the vulnerable areas in the case of loss of control.
When I last organized a small aviation event (more than 20 years ago) the regulator required me to consider all of these aspects (and we did close a public road for a brief period). I was also required to personally review the documentation for every pilot and aircraft participating for apparent compliance.
It was funny that two of the aircraft proposed for participation, had been flown in by pilots who did not posses a pilot's license at all! I quietly pointed out to them that not only would they not participate in "the games", but they should not even flown in at all - the the two neatly dressed guy over there were Transport Canada inspectors, so walk the other direction!