I think the average ex-JW or JW who dislikes Watchtower's shunning program is not because either objects to the notion of shunning but, rather, because the method used by Watchtower lacks transparency and employs star-chamber tactics.
By comparison, the biblical instance where Paul supposedly recommended a congregation shun an individual he went on to tell everyone the precise reason for his recommendation. Supposedly the man was immorally living with his own father's wife. Okay. So now members of that congregation knew the issue and could therefore decide whether they would shun the individual. Watchtower's program does not do this. The supposed "sin" for which a JW might be shunned for could be a completely moral act of demanding answer to a question that deserves an answer. On top of this we have the problem of star-chamber tactics.