As my specialist put it "if there was a common diet that cured people, we would know about it already". Anecdotally one never knows if their UC/Crohn's improves because of their diet or it's just part of the ups and downs of those diseases.
That said, I'm happy in general if I hear a fellow UC / Crohn's sufferer seems to have found something that works for them, especially something that is better for you than steroids and other treatments with severe side-effects.
That said, if I can get some placebo effect benefits from believing that reducing processed food helps, it might be worth doing -- if nothing else it reduces cancer risks :)
He is the inventor of the triple abx therapy for H.pilory so I would listen to what he says.
(Sorry, i'm in this thread because I have MS, and there are lots of scam diets claiming to cure it. They don't - at all. They mostly just make folks feel like they have control).