Mainly for 3 reasons:
1. They have a vested interest in presenting their therapy in an overly positive manner, as they sell it for hundreds of dollars per day at their clinic.
2. I've read a study published by them which contained some hyperbole that I can only attribute to either incompetence or deception [1]. In short, they described a newly diagnosed type 1 diabetes patient which did not need insulin when not consuming carbohydrates (completely normal during the honeymoon phase of T1D) and had an increase of C-peptide shortly after diagnosis (also a common occurrence for many during the honeymoon [2]). From this (and nothing else) they draw the completely unfounded conclusion that "the paleolithic ketogenic diet may halt or reverse autoimmune processes destructing pancreatic beta cell function in T1DM."
3. Their website contains language and phrasing that I would only except from charlatans, and not from serious medial practitioners offering an unproven and unconventional treatment. Such as "Get rid of the inconvenience of visiting doctors: We cure you." and "A final cure for your disease" (above references to cancer on the same page, no less).
[1] https://www.researchgate.net/publication/267810000_Type_1_di...