The point isn’t just that right-wingers believe in their own reality, but that they don’t think it matters that other people have different versions of reality. And no, this isn’t symmetric: liberals don’t consider it unnecessary to know what conservatives are thinking, or dismiss actually influential figures as marginal. Liberal may despise Rush Limbaugh, but they won’t dismiss him as a marginal figure nobody listens to.
In some ways, the right’s epistemic closure has been a source of strength; right-wingers certainly don’t negotiate with themselves. But reality does have a way of making itself known, eventually, and the right really doesn’t know what to do when that happens.