He's in an extremely abusive relationship. He's been in it all his life. People tend to stay where they're at until they literally can't any more. It's called fear of change.
I know it appears like nothing we're typing is making any difference, but we also don't know how far he's down the metaphorical path to independence.
I understand that it is an extreme situation, but if he just opens threads in this forum about how bad it is, without then ever trying something to get out, guess what? It won't help him! And like you already stated in following posts, there are institutions which can help him. He can even ask a psychiatrist or a therapist about his possibilities to get out, if he is seeing one, what I doubt.
And to seek help, he can use the INTERNET! It isn't like we are still living in times were this great possibility is not available. He can google for institutions or find a forum with people who are specialized in dealing with problems like his. And this is for sure not the right forum for his problems. Do you understand that?
You gave him now plenty of hints what to do, we will see, if he does anything you suggested to him, or if the next "My family is so horrible" thread is just around the corner.