He kept a straight face, and maybe even believed it a bit himself.
His efforts now to stay newsworthy doing things like moving the Ever Given are obviously tongue-in-cheek and funny.
There has never been any "debunking" needed because he's subject to the same physics as the rest of us. Of course he's not really bending stuff with his mind! People were just more ready to believe he had some special exception, and he ran with it.
Randi's obsession and anger (reflected here a little?) seems as old-fashioned and silly as Geller's spoon-bending antics.