Yes to the comments above.
When people naturally turn away from (shun) certain behaviors in others based on their own value system that is one thing.
It can serve to help the individual exhibiting the behavior to modify or correct their own course in order to remain part of a social group. That is a good thing, both for the individual and for the big picture of the group.
What the JWs do is set in place an artificial code of ethics determined by them and demand that it be followed to be part of their group. One way you can tell how very seriously it is off track from being normal or healthy is not only do they penalize the individual they are shunning, they will shun others who dont shun the individual!
To compound the idiocy of this they also keep changing the rules on what is shun worthy.
The JW rules are designed to exploit human behavior to their own ends.
That is hugely different than the natural giving of feedback to one another about personal behaviors in a group setting.
Most importantly, I am sorry about your friends pain and I am very sorry for what you are going through now. The fact that you are mulling it over and concerned shows that you really cared about this man.