There's a high number of battered women who return to their batterers and studies show this is primarily because they somehow are convinced that they were partly to blame.
In my experience, I think it's safe to say that most DF'd JW's on some level are still victims of the cult and are often convinced that they deserved to be disfellowshipped and shunned.
If this rumor about the high return of DF'd ones is true, it's obvious they aren't returning out of love for God. They are returning for self serving reasons.(can't blame them). Not only do they literally loose all their friends and family, they still erroneously believe that their eternal life hangs in the balance as well.