D of C, where in the publications does it say a person could be disfellowshipped for "continuing a relationship with an unbeliever." I can't find that, and I could use it in a conversation with a relative.
I recall that the situation fell under "loose conduct" in the past. A blatant disregard for God's standards to "marry only in the Lord". After reading Viviene's comment, I'll admit the guy may not have finalized his divorce -- just do not remember. He was an MS. The application was made by the WT Service Dept.
To go for it now, it could likely be "brazen conduct" (since they changed the Bible).
Of course, now there is no DF, so doesn't matter. A local case here the former elder has been online hooking up for over 3 months and filed for divorce and still no judicial action.
Should be fun to see how all these changes (and Pretend Changes") work out in the real JW World.