Where did you find this? I don't remember reading about it - could it be in his son's books?
One (possible) omission here - the sand trout traps water underground by linking and forming dams around water pockets - that’s the cause of Arrakis’ ultra arid environment, but maybe it’s also the source of nutrition?
Anyway, it is a bit silly indeed but in the novel’s context it feels grounded.
I put together the pieces mentioned in various places in the first Dune book. Every step sounds good and plausibly science(-fiction)-esque when presented separately, like the book does. Only when you put all the steps together, the picture starts to look like an M.C. Escher drawing.