You're missing the point. "Authorities are always wrong" is not only demonstrably false (I could have listed a dozen other examples), it practically invites the reader to think that reversed stupidity is intelligence.

I think you are heavily misreading the intent of the quote, if that's what you take from it.

The quote basically teaches the kind of relationship that Feynman had with authority. Don't believe in it just because they say so, but demand evidence and follow where the evidence leads you.

Feynman might have benefited from brushing his teeth more frequently but he still left the legacy he did because of his relationship to authority.