[Chuck Moreland]

Actually the bolt just has to rotate, and the torque-couple created by the offset mounting point of the bolt attempts to rotate the bolt.

Mattias, your reply shows that you understand my point. The small offset does help to keep the torque-couple small. But you will find there is surprising variation in the ID of the torsion tube. You will not always have such a tight it. With load and vibration rotation may be an issue.

Further, any repetetive rotation however minor may cause the bolt to loosen.