John is right. The clutch bearings are only grease lubricated. This is fine whilst the disengaged clutch is spinning for shortish periods of time whilst e.g. idling, but they aren't designed for constant spinning and I would imagine that towing with the rear wheel on the ground would just cause them premature wear.
When riding the Scoot, the clutch is 'locked up' and so the bearings aren't doing anything.