I humbly confusing concepts that are interrelated. The static equilibrium with a stable flight.
In the analysis it is confusing the center of gravity of the aircraft to the center of pressure (moving along the airfoil versus angle of attack and the flow velocity of the relative wind ..... .
Bring the stick forward to maintain straight and level flight is a property of a stable aircraft, since by design always intended that the center of gravity is forward of the center of pressure (which is where the aerodynamic force is applied) thereby lower the aircraft nose ..., because the moment of torque (weight-aerodynamic force).
Another point to note is that the static equilibrium of an aircraft can be divided into three categories according to the response of the aircraft to the disturbance of that balance (neutral, positive, negative), and that will not mean that is unstable. ..... but it reacts in a certain way to change state.
Interesting thread ......