You don't get it. The fiddle is simply kindling waiting for a match without some form of excitation. It's as inert and tuneless as a fuzz box. You're making the frightfully arbitrary decision by excluding any piece of instrumentation whose timbral source is not purely muscular. I guess we need to toss out synthesizers, too. Back when I owned a Hammond B2, I thought its timbre was appealing. Guess I was wrong. It couldn't have had timbre. Boy was I wrong when I saved up my pennies for a Leslie.A violin needs physical input of energy to produce sound acoustically, while a fuzzbox actually needs an audio signal to produce sound. It can't produce sound on its own, usually. So conceptually similar but different enough not to be confusing, I think.
Think about brass instruments. Now blow a raspberry. If you were skilled you could play tunes with just your lipe. I've seen many brass player warming up with just a mouth piece, playing scales and tunes. By your lights, attaching a trumpet, tuba, or trombone to that mouth piece wouldn't be according to Hoyle. The instruments wouldn't produce timbre because they couldn't be activated except by sound,. That doesn't make sense, Sorry.
Your exclusionary factor would disquality many if not most instruments generally conceded to produce timbre.