A significant doctrinal change such as this would most likely be printed in a Watchtower study article; not presented at the circuit assemblies.
I could only immagine the "can of worms" that a proclamation like this would open up. How exactly would the deffinition of "inactive" be applied? Would it apply to those who have stopped turning in field service time? Would it apply to those who haven't gone out in service in six months, but still attend meetings? What if a parent has both an inactive spouse and child? How do they shun their child, but not their spouse? And furthermore, how could a congregation shun someone who hadn't even been marked by the body of elders for wrongdoing?
I could only immagine the flood of mail that would pour into the branch offices asking for clarifications along these lines. This type of ruling would create so much ambiguity and uncertainty; people would never be sure what they were supposed to do.