Does anyone know the history of glider cloud flying in the USA? Was it ever allowed under FAR?

Was the prohibition part of the negotiation that allowed the XPNDR exemption for gliders?

If it were allowed, would it play out any differently in the USA than it has in the UK?

Did Lucky Chucker has an AH over Reno? Was he current with IFR? Did he practice IFR in his glider?

If it were allowed under the FARs, I think people would have proper instruments installed and training in motor gliders would be available in the USA.

Installing instruments that you're not allowed to use without declaration of an emergency is a rather odd state of affairs.