Try this counter: "Are you a linguist?" (No) "Well, I will still grant you and I both the use of language to communicate. Let us continue." A silly argument to shed a silly light on a silly argument.

Or ask if the authorities have everything figured out in an actionable form (no) then let us help them out with our outsider perspective.

Or say yes, I am the very voice of authority on this topic but don't be so ashamed and embarrassed by your ignorance that you stop now - please, keep lecturing. If they are swayed by the argument from authority then it is okay just to mock them.