Their seeking people out who've been inactive and who were at one time baptized, is done so that maybe they can lure the person back or
they can openly DF that person at the Hall, which instills a semblance of fear as well to substantiate their power over the rest of the flock.
What I would do personaly, would be to say you've done some research on the organization and found the doctrines false and misleading
and this is the reason for you leaving. This always leaves them confused and off balanced.
There is no necessity to be mean and abusive to these guys, just be tactfully firm.