technically correct
While being technically correct that anything less than 180 degress is class C, from the old days, whenever anyone mentioned class C they were making reference to 90-120 degrees of conduction angle and efficiencies of over 70%, usually over 80% while maintaining gains of 10-20 dB per stage. Solid state devices cannot match this especially at the system level with gains of 6 dB per stage and the 32% efficiency per stage.
My belief is that the class C nomenclature is used by manufacturers to warn the user that the price for cheaper circuitry is distortion.
Prior to 20 years ago, RF transistor companies warned against trying for class C because of the limited gain, and drive power handling capability of transistors. If you look at the transistors claiming class C today they are usually for pulse application where the low duty factor would make the bias current drawn during the inner pulse times consume more power than that consumed during the RF pulse.