No.
Because a and b are the geometric position of the lift and tail lift forces relative to the cg. What that is saying is that
(1) the further aft I place the tail, the more stabilising it is.
(2) the further aft I place the tail, the less trim lift I need from the tail.
BUT you cannot say that therefore the less trim lift there is, the more stabilising it is. They are two effects, both caused by the geomtric position of the tail, but NOT linked to each other.
Again, if I were to offload the tail by introducing a reaction force as a trim system (the Harrier pitch puffer I postulated earlier) then I could vary CLt as I desired, and destroy the CL*a=CLt*b relationship, but the contribution of the tail to the stability of the system would not change.
Alternatively, if I were to deploy trailing edge wing flaps that (magically) did not move the wing CP, such that a and b did not vary, I would need a very different tail lift to trim the increased CL from the wing, but the stability calculation WOULD NOT CHANGE ONE IOTA.
If we were to stop talking about CPs and use pitching moment in the equations, and AC/neutral point type discussions, it all becomes rather more clear.