A very good way to injure or kill yourself. That's probably one of the stupidest ideas I've ever seen. Just imagine yourself in a panic stop situation fumbling to get that thing released and your engine/bike/you slowed down.
The reason cars, motorcycles and most other vehicles have spring loaded to idle throttle controls is for immediate response in a bad situation. Electronic cruise control systems have the means to release when the brakes are applied or a cancel button is pressed.
This accessory might be fine for long distance, highway cruising on a motorcycle but has no place on a motorized bicycle.