I gotta agree with Hoss on this one,
Retricted limits the whos, not the whats, per 3.2


3.12 <snip> If restricted following the guidelines for Class B events, it should be listed as
“C-restricted.”

3.2. Class B Contest. Entry is restricted to, or preference or priority is given
to, members of a club or clubs; or to an organization affiliated with the
AMA; or to residents of a confined area, such as a city or county"


According to the oposite view of the rule,
they would have to list a club swap meet at the hilton as C-Restricted to no-flying,
how else would folks know to not fly turbines or 40% Yaks inside the conference room swapmeet.