I've ran plugs in my motorcycle tires for thousands of miles with no problems (I usually get about 5k miles on a rear with the way I ride, the sticky compounds I prefer and the torque of the bikes I choose). It's actually kind of unusual when I don't have a plug in a tire at some point in its lifetime.
I'd have no worries at all running a plug in a scooter tire that suffers FAR less abuse than a motorcycle tire. Way less weight, far lower speeds, greatly reduced cornering forces and lean angles, generally much shorter duration trips (when's the last time you rode 500-1000 miles in a day on a scooter?), and a whole helluva lot less torque, plus no clutch dumps or even much in the way of engine braking.
