OP you're acting too nice, why smile and wave and nod at somebody who has invaded your commute, put you in danger, made you feel uncomfortable and literally forced you to be part of his imaginery race ??. If that happened to me I would of slowed down to annoy him and hopefully he would pass me. If slowing down didn't get that asshat off my back then I would of told him to stop drafting me and keep his distance.