there are micro switches in the throttle and TORS box on the carb, when the throttle is in it's resting position or is left off completely while riding, it triggers the switch, if the switch in the carb doesn't match that, the TORS brain cuts the CDI box to just an idle.
this is to prevent an uncontrolled power situation if the carb were to stick open, either by a sticking or broken throttle cable, or slide hanging up in the carb. so if that would happen and the rider leaves off the throttle, but the carb slide is still up providing fuel/air, it shuts the bike down.