[Note: in this post, he uses the word "witch" in reference to non-Christians who point out Christians' hypocrisy]
The point is to deploy the test as soon as the suspected witch tries to claim the high ground by co-opting Christian morality. In that event, declare the verdict; then block AS SOON AS SHE FAILS. Under no circumstances should you continue interacting with a confirmed witch. If she is the subject of extraordinary demonic activity, the demon can retaliate if your command could be interpreted as being directed at it--for which a case could reasonably be made if you've determined you're dealing with a witch.
I can't stress this enough: DO NOT TALK TO CONFIRMED WITCHES! Declare their lack of moral authority and block immediately!