snypher: You can do them with one hand. [Ed. This is ambiguous and could be read as "one hand, simultaneously". In fact, doing it with one hand non-simultaneously would be a weird claim to make of a simple knob. See also ajb's comment below.]
zihotki: Really? They are not close together and have a spring mechanism. [Ed. Seems to believe snypher is claiming simultaneous operation.]
Context is both these switches being turned off with a 1 second gap. Doing it with one hand simultaneously would possibly explain it, otherwise it doesn’t seem relevant.
What I gathered from comments here is it's not a simple flick of the switch and it actually takes some effort to turn them off. Can you really do it twice within the span of 1 second?
You pull it out and flip it. It’s not easy to do inadvertently. But it’s also not convoluted—you want to be able to quickly cutoff if there is an engine fire.