Who the what now? “Monologue” can’t be a false etymology, because it’s not an etymology at all. It’s a word. And the only conceivable etymology I can see for it is the Greek roots for “one word”, meaning only one person speaking.
No cite, but I do recall reading that Chrestus was not an uncommon name, and this helps to explain why people who are only vaguely aware of the Christian movement might have formed the impression that the central figure was called Chrestus.