In the Shepherd The Flock of God Book, elders are given direction as to when a judicial committee should be formed. Item 10 provides some examples of "brazen conduct" and starts as follows:
10. Though this is not an exhaustive list, brazen conduct may be involved in the following if the wrongdoer has an insolent, contemptuous attitude made evident by a practice of these things:
• Willful, continued, unnecessary association with disfellowshipped non relatives despite repeated counsel—Matt. 18:17b; 1 Cor, 5:11, 13;2 John 10, 11; w81 9/15 pp. 25-26.
Child sexual abuse and dating a non-believer are also in this list - nice to know where they all rank...
Anyway, the point is that simply talking to a DF'ed person is in itself not a DF offence, it's the "brazen" disloyalty to scriptural and divine (read JW) process by continued association and requires repeated counsel.
Elsewhere in the book it is clear that elders risk (note risk - not an automatic revocation) their privileges if they allow a DF'ed family member to live in the house. This is inconsistently applied and is a neat way for bullying elders to pick on weaker elders.