Well, he also denied the smoking - lung cancer connection.
I cannot tell you how many people would argue with me - IRL and online - often molded directly after Rush’s style, and repeat, like good little parrots: “correlation is not causation! correlation is not causation!”. I think Ayn Rand had her cult members smoke as a matter of dogmatic adherence to her Objectivist ideals, too. I have to wonder how much of this made its way to all the little Libertarians and/or Republicans as a consequence.