The wire is overcoming weight. It has no effect on roll, so if your explanation is correct, the model should be laterally stable despite there being no slip. Do not confuse TOTAL lift (acting in the vicinity of the CG to overcome weight) with LIFT ASYMMETRY (ignore weight, just focus on rotation in any axis about the CG.
Here's another example, FWIW.
Consider an aircraft at 70* angle of bank in a steady turn. With skilful rudder application, the pilot perfectly prevents slip. The aircraft has dihedral, so the lowered wing's lift vector has a greater vertical component than the raised wing's lift vector. Will the aircraft roll wings level without aileron input? No, there is no slip, therefore no asymmetric lift, therefore no rolling moment about the CG.
(Yes, the raised wing is travelling faster in this case, but we shall say the aircraft is descending slightly also, putting the lowered wing at greater AoA. So each wing is generating precisely the same total lift - in this example!)