The characters in Henry Fool don't talk in the slightly stiff, thoughtful deadpan that Hartley is known for, perhaps because of the absence of the director's usual avatar, Martin Donovan, whose highly mannered way of speaking has become almost a Hartley signature. He's very open to whatever the actors were throwing out. The tone and texture of this film are very different from Hartley's other movies. Hal's just trying to find physical ways to represent that. The scene where Henry's on the toilet, basically shitting his guts out, it's hilarious, but it's also more than that.
Henry enters the film as a mythic figure.
He comes over the hill almost as if Simon has summoned him. When he's on the toilet, you can't get much more human and vulnerable than that. It's not just there to shock. It's saying, yes, this guy is kind of larger than life, but he's subject to the thousand natural shocks the flesh is heir to. Those scenes are metaphorical in addition to perhaps being sickening.