Paul was harsh concerning the bloke who was sleeping with his father's wife. And the congregation took his words to heart. In 2 Corinthians, Paul seems to revisit the situation and suggests that the congregation are overdoing the church discipline. That the subjects of that discipline are showing signs of repentance and yet the congregation are still treating them badly instead of showing forgiveness and acceptance.
Unfortunately, the WT is only aware of the first point, and not the counterpoint, in their application of church discipline.