I never said that it took zero energy to spin the prop. A prop is doing zero work in a static thrust situation because the thrust is not moving the load. Work is force X distance. Power is force X speed. If the planes speed is zero, than the power delivered to the plane is zero. All the force in the world X zero equals zero.
It's like a car that is not moving at a red light, it is getting zero miles per gallon. A humongus Hum-Vee and a 50 cc motorcycle both get zero miles per gallon while stopped at a red light but one is still burning a lot less fuel than the other.