If he was right, the nuclear power plant at Ft. Greely wouldn't have over reved and blow the bearings so may times that it was decommissioned. There is very little spinning reserve. A fraction of a percent, at best. To use the grid at full power all night will require full fuel conniption, 24/7. this will reduce the usable life of the equipment, and cause more failures requiring downtime for repairs.
The 60 hZ frequency is a balancing act between the energy supplied to the generators, and they load on them. There is no way they can be running at full power and the same load, without speeding up.