Just like my brother and sister (when they were babies) sucked on Tupperware container lids and other plastic objects (and lead painted toys that are now known carcinogens) when I was a kid and never died.....
I might assume that unconnected wires "might" be the same sort of thing for a cat. And if I had money to wager in a fake bet, I'd wager that sucking on a plastic wire in and of itself won't decrease a cat's lifespan. I do not know this to be true, but in a fake bet that's how I'd wager.
Yes of course it's possible that a cat will swallow a plastic wire so yes it's safest to say "No". No equals zero risk. No is always safest.
Obviously nobody wants to give bad advice and nobody wants another pet to suffer... But if you know your cat won't swallow a wire in the same way that you know it won't swallow a rock, personally I see no issue here so long as the wire itself won't make you sick by chewing on it.
For me that's the only unresolved issue and because I do not know the answer it's safer for me as well to say No it's better if you do not allow this.
.... and it might be difficult for anyone to give you a "yes it's okay" answer because anything is possible, anything can possibly kill another creature and litigation is everywhere.