Because it is using power from solar panels to accelerate the ions, that's what makes it not a perpetual motion machine. We know we can build ion thrusters that

Because it is using power from solar panels to accelerate the ions, that's what makes it not a perpetual motion machine. We know we can build ion thrusters that generate enough thrust to overcome the drag at these orbits. But that is with different propellant. The question is if you can do the same using air as the propellant, and with even higher thrust to account for the additional drag a scoop would have over an aerodynamic design.