As said, it is viewed as disassociation (which is the consequences as being disfellowshipping, namely shunning) if the elders decide to go after them.
The question is why they haven't gone after them. I think John Free pinpointed a possible reason...they've are overworked. I believe quite a few elders don't actually want to play judge, jury and executioner, and sometimes will procrastinate doing so or defer their responsibility to someone else.
Of course, when the CO comes to town, he might prod the elders into action...