When a JW has a DF'd person on their facebook account, there could be two reasons.
1. They haven't been to the 2009-2010 Special Assembly Day yet. Or,
2. They aren't going to let the WT decide who they can talk to.
Back around 5 years ago there was a Service Meeting part about not being on Facebook AT ALL. Don't know whether it was just in certain circuits or all over, but it's clearly out of sight/out of mind right now. LOTS of JWs on Facebook, and quite a few with DF'd people as Facebook "friends."