“It is literally impossible to have an eyewitness account of something causing autism.”
Exactly. Anyone who claims to have witnessed such a thing is a liar. All anyone can say is that such-and-such a thing happened shortly before the child was diagnosed. NOBODY can say that the diagnosis would not have been exactly the same had that thing not occurred. Nobody knows what causes autism, but the most likely explanation is that it’s genetic, which means nothing anyone does or doesn’t do can either cause or prevent it.