New here but had a moment of this with my Streaker rehab.
The Predator and similar small engines have a magneto ignition. The current to fire the plug is generated by the rotation of the engine. With the switch on, the switch is open, and engine rotation sends current to the sparkplug. With the switch off, the switch is closed and the ignition current is sent to ground and theres not enough to fire the plug. The opposite of most automotive stuff.
I put a switch in series with the predator off switch, and with both in the on position, as marked, turning the second switch off had no effect. it kept running. Thinking it through, with the first switch open, closing the second one had no effect. Turning the first one off allows the second switch to control the engine.
Check into this.