Actually, from my experience the ex-jw groups just like to talk among themselves, and pat each other on the back that they've "escaped" the org., rehash old memories, and tell themselves how much better off they are now. They don't really like "JW intruders" stirring things up. They usually tell them to go away.
I have posted on both the “Jehovah’s Witnesses and the ‘exjw.’ There is even a loyal to JW subreddit that I have posted to. I visit there sometimes—But I live here. I also have my own page there. I haven’t quite figured out how reddit works and I find navigation there a challenge.
What is interesting about your comment, is that the reddit site where you posted your book is not the "exjw" site, but for "Jehovah's Witnesses". On there, you will find both JWs, and exJWs. Just like here, where you visit frequently, and post regularly.