Fool! You think I know what the difference is?
spoiler
This is a sarcastic, over exaggerated reaction. Just so you know I'm not actually trying to insult you.
No, really, I think I understand even less now. And how is the word "fiddled" being a verb change anything?
The term "fiddling/fiddled" implies there is a fiddle involved. My problem with the statement is that there couldn't be a fiddle involved. Because fiddles were not invented yet. Lest Nero was fiddling himself (or someone else), I cannot accept your version of the idiom as correct. Just because there is no such thing as "luteing" or "lyreing" doesn't mean "fiddling" is the correct verb to use.
Edit: I think I know where the misunderstanding is coming from. Are you assuming I am disagreeing with any part of your statement? I am not. I am simply saying that the correct version of the saying would not mention fiddles. Because there were no fiddles. Unless that is the point. We know he wasn't playing the fiddle because there were no fiddles? Is that the point?