Just look at the Bob Hoover medical fiasco in the 90s. All of the pressure in the world from citizens, and even legal action up to the country's highest courts had zero impact.
Ultimately the solution to Hoover's grounding was him personally convincing one person high up enough in the organization (the FAA Administrator!) to change his mind.
I don't think there are enough race fans who care to invoke enough political will to make the FAA change their mind on the race course rules. If the unlimiteds stop racing because they don't feel they can safely comply with the rules, I'm sure the FAA wouldn't even notice, much less shed a tear.