i wouldn't say that there might not be some reason why the WTS couldn't go after you for some legal reason, like maybe if you posted some copyrighted info beyond what is legally permissible, but for the most part you or individuals don't have to worry about the Society coming after them for partipation on forums.
what you should be MORE concerned about is the use by potential employers or clients, or even potential significant others, competitors, etc. etc. that any of these persons might make from anything you post online in this forum or elsewhere on the Net.
there are tons of scenarios where you might not want someone to know that you are, were, or even care about Jehovah's Witnesses or to know any such person info about you. if you are so concerned then take steps to minimize your exposure.
Also consider that anything you put on the Net, even in any so called "private" pages, etc. could eventually be made available to someone you have not anticipated, made generally public, or might be discoverable in legal process. It is also potentially "forever" or extremely long-lasting and might be used for some purpose many many years from now.