You are correct, maybe I oversimplified the problem. When I said "started to orbit" I wasn't implying the bodies would complete the orbit, but then I negligently stated that the inner body would complete one revolution before the outer body, which deserves your criticism. What I should have said is that, since the outer body has to travel a longer distance in order to stay aligned with the inner body towards the central mass (conjunction configuration), it would get behind the inner body because they have the same linear velocities.That's not possible, at least not if the orbits are circular
Following your logic, when the bodies are supposedly stabilized in tidal lock, we will always have a greater force from gravity on the inner body than on the outer body, so there's a tendency to increase the distance from one to the other. Also, the force that would cause the torque has to travel through the spring until it reaches the outer body, at a later time. As a result, the outer body will always be behind, and this is precisely the shearing I was talking about in the beginning of this thread. When you have torque in the real world, you can be certain that you'll get some shearing.Now look at the torque around the center of mass of the body-spring system when the outer object is leading and when it is lagging; we know that there will be some torque because both the direction and the strength of the forces on the two bodies is different.
When the outer body is leading, that torque acts against the rotation, and when the inner body is leading that torque tends to act with the rotation. That is, when the body-spring system is rotating around its center of mass at less than one rotation per orbit, the torque from the different forces on the two ends acts to increase the rotation rate; and when the body-spring system is rotating at more than that rate, the torque acts to reduce it.
Ok, plus shearing.Thus, we expect the system to stabilize at exactly one revolution per orbit, and that's tidal lock.