As incredible as that sounds that actually what he said. I very nicely
told him of the many, many, many errors the Watchtower has made and told
him to read the Feb 2017 Watchtower which confirms they're neither
inspired or infallible. Then i asked him where does the "new light" come
from if they're not inspired?.
First, I find your post so interesting. I relate to it in many ways. Thank you for posting. I find very interesting what i quoted from you. I'm glad that you redirected him to the actual bible, making the difference between the Wt publications and the bible.
Being the way I am, I always try to look at things from different angles. Yes, it's true and great that he may be understanding what you are telling him. However, I'd suggest to be sensitive to his reasons to take bible studies. Seems to me that as is, JW means recovery from his bad decision making. He may not be in a place where he can make a connection between his recovery and taking responsibilities for his own actions.
What I mean is, if you persuade him that the WT is not good for him, he may not feel like he can find anything to shelter himself from making bad decisions. If he's using the WT as a way of finding a way of having a healthier life, aside from what the WT teaches, I think you should address many non-religious healthy ways of living and maintaining a healthy lifestyle.
His WT background may have influenced in the bad decisions he took when he left. Point that the WT not only teaches how they are supposed to be as JWs, but also indoctrinates and convince people of what they are supposed to be if they leave. Some people have a hard time understanding that "what happens to people when they want to experience the world" indoctrination. That negative influence is precisely what had caused many ex-JWs going into the world with no life skills (especially those born in) and get them in trouble.
It is great that you may be getting through him, but please consider his real reasons to become a JW, and those seem to have nothing to do with the Bible, not any of the JW teachings.