The issue about "Scriptural" separations has only to do with 1) whether a brother will continue to be used in an "exemplary" way; 2) whether the departing brother or sister can expect to have the support of the congregation (perhaps including financial aid).
Technically, that is true.
But remember what it was actually like to be in the Borg, Craig. Most witnesses weren't concerned only with sanctions, and what they could get away with. Many--if not most--would follow the Society's directions, even if there were no overt sanctions, because they believed it was the right thing to do.
If a person does go ahead and leave their mate against the Society's guidelines, they have a major guilt-trip to try to overcome, at one of the most emotionally difficult times of their lives. Plus, they will be regarded as spiritually weak, which in some--though certainly not all--congregations, means that they will be a social pariah.