08,
the kill switch has nothing to do with what speed your going. Like Old Geezer said it is federally mandated on just about anything that has an engine, from Jet Skis, boats, lawm mowers, and yes motorcycles and scoots. My John Deere riding lawn mower has one under the seat that drives me crazy. If you get up from the seat it has a pressure sensor that will kill the engine. Evidently this was installed to prevent the mower from continuing to run if you fall out of the seat. But your scoot speed has nothing to do with when it kills the engine.
Mike