[sofal]

I think a big part of the reason why hubris is bad is because it causes you to make mistakes when determining truth from error. If someone goes around telling people a claim is false without sufficient justification, and they're doing so as a reaction against people believing in the claim for bad reasons, then you could say that their hubris (or something like it) caused them to make an error in judgement.

There is a difference between saying that a belief in a claim is not rationally justified and saying that a claim is false. Both sides of these debates can make mistakes. Those against believing in the claim can make the counterclaim that it is false, and they might not actually have justification for that. On the other hand, often those that believe in the claim misinterpret the other side as making the counterclaim when they are in fact not doing so.

In the case of autism there has been extensive research since the moral panic began, and no evidence for a link has been found where it was expected to be found, thereby bringing increased justification for the counterclaim. I think this is also true with many other unsupported claims out there that are popular enough to have been exposed to systematic scrutiny.