Well, 2 reasons why that I see are:
1. The icon in the upper right says everyone welcome. If it was strictly ex-jw, then only those people would feel welcome.
2. This board was started as a regular JW discussion board, back when the light was separated from the dark. I remember looking at the first few posts a while back and noticed that people were talking about field service and book studies and all that boring stuff. Right now, its open to anything related to JWism. for and against :)