The whole point of that illustration, and I cannot emphasize this enough, is to plant in the minds of the congregation the idea that apostates can appear as one of them! She is modestly dressed, she is presentable, her meeting bag is on her arm. There is nothing to identify her as one who is an apostate whether it be spiritually or morally.
The congregation is being taught to TRUST THE ELDERS as the only ones who can identify an apostate!
It is an insidious image carefully crafted to plant mistrust of any who may appear as one of them but has asked too many questions.
Frank