Whether he's coming or going

Speaking to a capacity crowd at a California Republican party convention on Friday night, Bannon said: “He embarrassed himself. The speechwriter wrote a highfalutin speech. It’s clear he didn’t understand anything he was talking about … He has no earthly idea whether he’s coming or going, just like it was when he was president of the United States.” (Bannon on President GW Bush.)

What does no earthly idea whether he’s coming or going exactly mean in that passage?