DOC, I guess if you really start some very public activism, or are helping JW's to wake up, as I do, then they may target you.
It all seems so very petty and small minded, but then, they are. I reckon if they deem it too long ago that you were a member to make it worthwhile DFing you, then they will DA you and let it be known, so that JW's steer clear of you anyway.
It still seems strange to me that they deem it sensible, or even acceptable to people looking in on the Org, to take action against someone who was a member many years ago. If anyone had the money, time and will to do so, I think a Court case for defamation or something would be a fun thing to do, to lay before the Public how very childish and silly they are. What proof could they offer a Court that you had been a member ? no Record Card, just hearsay evidence from people who remember you. I can see the JW's being laughed at in Court, and paying some damages.