Back in the day, disfellowshipped individuals sat at the back of the hall and, even if attending with their still-in families, still sat at the back. I particularly remember a brother had committed adultery with a younger sister in the congregation (which resulted in his divorcing his JW wife).
That brother and his "new" wife were both disfellowshipped but within 15 months were both reinstated. But before that happened they both sat at the back of the hall.
And there the usual problem drinkers and "promiscuous" ones who seemed to go through cycles of being out then back in then out again.
No one questioned it.
Looking back I am amazed at this bizarre "practice" - and I cannot even quote a Watchtower in support of their sitting at the back - unless I missed something in the literature back in the 1960s?