I'm pretty sure it would result in the US internet being isolated from the rest of the worlds'
Which actually works against Putin since that means his troll farms also get cut off, meaning less new material for the useful idiots to keep other useful idiots freshly indoctrinated with.
Because generally where the West can extend their communications the people tend to provoke change for the better.
Cutting Russia off entirely for the troll farms is locking Russians into a Russian curated echo chamber, or a least doing that to an even worse extent than Putin is already trying to do himself.