Is it not fraud to claim a scientific backing behind the concepts, when no such backing is provided, and likely doesn't exist? Is it not fraud to claim to be an "expert" in a field in which you have no formal training and likely no practical experience?
Those two points above are what I walked away with as the claims along with as much proof as they could muster. Because they can't prove that there's not something that scientifically credits DiSC, but they can say that they did not find anything. As a bonus, they're also clearly intellectually honest in asserting that they could also not find anything discrediting DiSC. They also conveyed what they could not find regarding the author's education and experience. I'm not quite sure what more you are looking for here?