I wouldn't want to bother with a frayed cable that close to the pinch bolt.
If it's after the pinch bolt, it will make precisely no difference at all. Other than looking fugly. And making your fingers bleed if you try to wind the fine, pointy and ouchy strands of the cable back into place.
"precisely no difference at all" Not something I, or any other qualified mechanic would let back to a customer without the very simple and cheap job of doing it properly though.
Isn't a new inner going to be cheaper than buying steel putty!?
I wouldn't want to bother with a frayed cable that close to the pinch bolt. New inner cable + end crimp should cost less than a coffee in London.