Dan,
"I suspect they will find some rule underwhich they will begin overseeing this road."
As I understand it, the rules of the FRA are written as such that they have jurisdiction over anything with a flanged wheel, from the UP main line all the way to the N gauge layout in a friends bed room.
OK, that may be a slight exaggeration, but I have heard it said by several people that technically live steam tracks do fall under FRA rules. They just don't have the time, man power, money, want, or legal need to oversee everything. Mainly they just oversee/inspect operations that if something goes wrong they could be sued for neglience.
Cheers,
Curtis F.