From 1977 back to 1975 the AFM had the safety fuel cut feature. On these years you could turn the key on, remove the plasic cover on the AFM, then rotate the AFM mechanism to turn on the fuel pump.
In 1978 they changed the fuel safety cut to route off the oil pressure sending unit. Same principle as the AFM method, no air flow, no need to continue fuel pressure, no oil pressure, definetly do not want to continue fuel!
As Larry points out with the alternator & oil signals, there is a redundency in the system.