I played a few scenarios using the M60A3 tank. After the last update is fine, AI loader will stop turning off stabilization to load the gun if the vehicle is moving at slow speed.
Like Wiki say:
"The M60A3's stabilization system allows the tank to effectively engage point and area targets at speeds between 16 an 34 kilometers per hour (10 to 20 mph)"
"When firing on the move, if the vehicle is traveling faster than 20 kph ["slow" speed on a route] then the loader will disable the stabilization system while loading the gun. Once the gun is loaded, the gunner can re-enable stabilization by pressing the V key (simulating flipping the STAB switch on the Control Selector Assembly to ON)"