I think that if one was to be involved in a murder case, the person pulling the trigger takes all the blame. You could never say that the bullet has some blame, even if a tiny one.
I agree that there might be those JWs out there that see shunning as a realization of power. A way for them to channel who they truly are. Steven Hassan explains in his book that someone that is under cult indoctrination does not loose free will and his abilities to make choices, but they do loose the choices themselves. i.e.: before being a JW, a situation may present you with choice A,B and C. After being indoctrinated, option C may be out of the pool because you were indoctrinated to think the bible speaks against option C, even though most reasonable people would not see it as such. You still have free will, except your options are now limited.
I don't care how much you know about the health benefits of salads, if someone managed to convince you that the salad is poisoned, you will not eat it. This happens to all of us day in and day out. Some people are afraid of flying to the point they won't fly at all, yet they have no problems texting and driving all the time. This only changes when you have a major awakening. People have awakenings to all sorts of things, not just from cults.