Yes, all of that is surely true, but until it gets to that point, there is no way to stop a runaway diesel engine except cutting off the airflow ( if your lucky ).
I saw an old Cat D7 once that somebody had overfilled the air cleaner (oil bath) on that went "runaway". The operator didn't know exactly what was happening and though the fuel injection was malfunctioning. He grabbed an axe and started chopping at the injector lines thinking he'd cut off the fuel. This was an old external pushrod motor and he did manage to stop it because the axe bouncing off the injectors had bent/dislocated enough of the pushrods that it couldn't run any more.