@gone for good:
This is getting a bit painful. Having a document signed some time before you appear “on the elder’s radar” won’t change the outcome one bit. You say:
Their ecclesial authority has been preempted by your having already exercised your right to emancipation
And conclude that they can’t DF you. They really don’t care to DF you because you are informing them that you don’t consider yourself one of Jehovah’s Witnesses. It doesn’t matter that you made the decision one month ago or ten years ago. Once they know that you have decided to leave, then they will inform everyone about your choice to leave. They will announce you have disassociated yourself. There won’t be a committee. There won’t be a disfellowshipping. They will announce you have disassociated. The elders are not exercising any authority over you. Actually, they are doing the exact opposite and acknowledging your free choice to leave. Congrats! You are out. Now they will shun you.