A Freewheeling prop creates vastly more drag than the same prop stopped (unfeathered). A stopped prop only has form drag. A rotating one adds aerodynamic (rotational) drag. All sailing boat owners know this.
Perhaps that's why boats never get off the surface.
A stopped prop is still an aerofoil being dragged through the air or water. It creates lift, and therefore some associated induced drag, as well as form drag. So does the windmilling prop. I can see no reason why in principle one should be draggier than the other. Here's
another paper that makes it clear that the trade-offs are more complex than you would like.