I was just pointing it out for the sake of those who didn't know any better. I don't have a source from SAE, that I know of, regarding intake restriction on any level.
I will note, however, that only for Otto cycle and 2-stroke gasoline engines is an air-throttle actually necessary, and there are actually DI-type gasoline Otto cycle engines which no longer require an intake throttle. Their speed/power is controlled by load and fuel input, like a standard compression ignition engine.
I'm not sure that it's entirely relevant to the OP's question, but you (Maestro) mentioned earlier that throttling restriction was necessary to make an engine run "in a controllable fashion" and didn't clarify any further.
Welcome to EM, by the way. Maybe try a proper
introduction?