Interesting points Alan. I never understood WHY they bother DF or DAing someone.
It's irrelavent because they can de-facto shun someone. Don't underestimate the power of "marking" (an unofficial sanction). For example with the Andersons, all you would need would be for every CO to mention that "due to laws of Caesar, what is bound in heaven cannot always be bound upon the earth. However, we know how Jehovah views those casuing divisions in the congregation. If we are spiritually mature, we will not listen to such ones. etc etc". Then, allow the "elderette" gossip machine to "unofficially fill in the details."
If you want to go further, you can get restraining orders against the individual, so that they cannot set foot in a KH. Claim they made a threat against the congregation, and turn it into a game of "he said, she said."
I've seen it work at the circuit level when a "well-known" elder went apostate and threatened to sue if they were disfellowshiped. Yes, his old congo ended up successfully getting restraining order against him (trumped up charge of him making a threat; but 2 elders claimed to have heard). No formal announcement from the stage, but the net impact was the same.