Yeah, it counts as if the champ is wandering in a specific direction as apposed to knockback for some reason. I definitely think unstoppable should prevent repulsion though imo.
Doesn't iron will stop it already? I've always thought of repulsion and fascinate as being mental forces rather than physical ones, so iron will makes more sense.
Knockback is a physical movement that is stopped by terrain/champions and deals damage. This is prevented by Unstoppable. Repulsion/Fascinate are psychically compelled movement that causes a person to walk in a certain direction and does not deal damage. These are prevented by Iron Will.