Something about a letterhead from an attorney, throws in a protocol, lawyer to lawyer process and privileges. Then that letter must be sent to the WT Legal Department. Slows things down. I know of a few cases where, though there wasn't a 'formal announcement' made from the platform, there still is under the current 'shunning' done. However, at least some JW parents then feel justified to speak with their grown child, since it wasn't 'announced formally.'
Timing is the key too, as once the announcement is read, then it's too late.
Best wishes!