Shunning is a tough one siince my exposure to DF'd people was limited. I remember saying hello to someone who was DF'd when I saw them in the street and then felt guilty for years afterwards.
I also remember sitting next to df'd people at the hall and trying to be friendly and sharing books with them since they were making an effort and it seemed churlish to be mean to them when they were trying so hard. We once saw a df'd person who had run out of petrol and took him to the petrol station and back so he could fill up his car. It never occurred to us to leave him stranded.
I also know that if any member of my family had been df'd I would never have rejected them. In my mind df'ing was a loving discipline to bring someone to their senses not an act of rejection and I therefore lacked the essential coldness that is required to treat someone who is alive as if they are dead. However I was in a cult who knows how the constant drip feeding of poison would have affected me in the long term.