If you break the ground it should cut off. It can't run without both. Of course,I know that you understand that.Just saying. I think he wants to kill the fuel just to prevent a spill or prevent a damaged hose/line from spewing-that sort of thing. I didn't understand it to be a means to kill the engine. If that was the idea,then yeah,kill the spark instead. Doing both is a great idea,too.