I disagree. "Authority" in "argument from authority" does not necessarily mean an expert, just that it's an argument whose validity depends on the character/rep

I disagree. "Authority" in "argument from authority" does not necessarily mean an expert, just that it's an argument whose validity depends on the character/reputation of the person making it. E.g., "he said/ she said" with a police officer, in front of a judge, is a losing proposition.