Keep in mind, that in doing so, he has given up any hope of ever seeing his family again. Rinder hasn't been allowed to see or speak to his children in 12 years, and he is never likely to see them again, ever. The Cult forbids any contact.
Furthermore, the Cult has created websites in Rinder's name, claiming that he has never shown any interest in his children, that he was a wife beater. Here's just one of them
http://www.whoismichaelrinder.com/a...de-after-more-than-30-years-of-marriage.html#
(there are many like this but I don't want to link any more because I don't want to give this cult any more oxygen)
His family will have been thoroughly brainwashed to implicitly believe all the bad things the Cult of Scientology says about him.
If you are a member of the Cult of Scientology, you have to know that this is what you will have to face for the rest of your life if you leave and then speak about your experiences. Now its very easy for you to say he could have just walked out, but you need to understand that "just walking out" has very dire consequences.
Your approach seems to be a lot like those who argue that battered women can just walk out of a bad relationship... IT DOES NOT WORK THAT WAY. Stark fear is what keeps battered women from leaving; fear of the consequences if the ex-partner comes looking for her and finds her; fear of what will happen if she gets caught trying to leave. The Cult of Scientology is very much like a vindictive partner who beats you up to keep you in line, and who comes after you if you leave, or try to leave. Just walking away is not as straightforward as you are trying to imply.