You are, unfortunately, incorrect. The Magnus effect doesn't gain you anything other than the helpful drag of a tall cylinder when going in the same direction as the wind. Rotating it only pulls you sideways, which doesn't help.
However, it can pull you forward when the wind is coming from the side. You change the direction of rotation based on which side the wind is coming from.
Without tacking, no (edit: solely) wind power systems will help when going straight upwind.
He was right that "The Magnus effect doesn't gain you anything other than the helpful drag of a tall cylinder when going in the same direction as the wind."
In fact, the Magnus rotors will not provide any usefull thrust is both upwind and downwind scenarios.
However, it can pull you forward when the wind is coming from the side. You change the direction of rotation based on which side the wind is coming from.
Without tacking, no (edit: solely) wind power systems will help when going straight upwind.