As horrible as this is, it's fascinating from a psychological perspective.
Republicans and their supporters in the Trump era (and now beyond) keep brushing up against a wall: they either have to keep embracing increasingly obvious falsehoods or crack and repudiate Trump.
Oh, sometimes they'll embrace or reject things out of political expedience (see: Mitch McConnell), but then you get people like Shirkey, for whom this appears to be a mental defense mechanism: he can't accept that the Capitol riot was real, because if he did it would collapse his entire world view.