Assuming that is the case, which frankly, would make his Bankai just pure shit, Aizen isn't aware of that and has no reason to assume it stops sharing damage in the following acts, much like Lille who didn't try and attack after Shunsui explained it.
Yes, I gave my opinion, it's clear to me that the thread automatically wraps around the opponents neck as we're never shown Shunsui doing anything to indicate that he's wrapping it around, I can't definitively prove it's automatic and you can't prove it isn't, so why go in circles about it?