That is not a valid scientific study, it is a website for a book and to sell products. Posting links to mere commercial websites is not scientific proof.

The scientific study the author referred to was not identified completely, nor even by name. The only actual governmental letter simply indicated that DE does not harm the internal organs of the animals, but mentioned nothing of any health benefits at all, let alone confirmed that DE was even wormer at all.

The difference between what you're posing and what I am posing is I have posted actual studies by accredited universities directly stating that their actual research showed DE does not kill worms.
You keep posting links to commercial enterprises "claiming" that alleged studies "showed" DE work, but no links to the actual studies themselves have yet been provided, thus making them empty claims.

You need to recognize the difference between the actual published scientific study itself ... and some guy trying to sell a book and a products "saying" he read one.

Jack