While I appreciate that it is more exciting to see the aircraft banking 60 or 70 degrees and it is quite difficult to get an idea of the scale from the diagram I would have thought it was crazy to fly aircraft at coming up on 500MPH in an arc that requires them to have control to keep them from going off the arc into the crowd.
In my mind, from hearing rules and guidelines, I would have thought that the only possible way to lay out a course would be with the long straight parallel to the crowd line and the last turn perhaps a mile or so before. That way the aircraft should be straightened out before entering the vicinity of the spectator zone.
An alternative, perhaps, would for the spectators to be within the race circuit, with usual distance clearance, then any fast aircraft going astray is far more likely to crash outside the perimeter. Some of the best views and pictures I have taken have been of aircraft flying an arc concave to the crowd line seen in almost plan view but some shows I have been to have been constrained by traditional air show mindset and a total lack of imagination on the part of the organisers. One in particular uses the longest runway as a dispersal and static show and sits the crowd on the North side of the runway in use. It is nearly impossible to get a good picture and on a clear day even to watch the aircraft comfortably because they are against the sun. Doesn't anyone think of these things?