I do not believe aerodynamic stability depends on whether the inputs change or not. For instance, stall a Cessna 172 and it will tend to pitch down on its own even if you keep pulling on the yoke.
Also an aerodynamically unstable plane isn't a plane in which a stall is irrecoverable. It's a plane that, left to its own devices, will not make things better for you.
Also an aerodynamically unstable plane isn't a plane in which a stall is irrecoverable. It's a plane that, left to its own devices, will not make things better for you.