Diagnosis of autism has never been based on specific genetic or biochemical causes or mechanisms. It is defined by its behavioral symptoms.

> which has different causes, and manifests itself on a different brain structure and is unrelated to any gut bacteria whatsoever

How do you know it has different causes, when the causes of autism have not been enumerated?

> Why this crap is considered to be a respectable science?

I'm glad you don't get to decide. Maybe this will turn out not to have any impact in humans, but why not let the research play out - that's science.