I'm sorry you're going through this. I remember what it was like for that religion to be my entire world. I remember friends leaving that world and wondering how they got so messed up.
I was homeschooled too. I was an MS. I stopped going to meetings abruptly, I had to be chased down for elders to get me to officially leave. So I know how all this looks. I can't tell you what his reasons are, but I can tell you what mine were: I never really believed. Not really. Amidst the baptism, the service, the pioneering, the talks I gave, it was all just following along with the life I was given. Then I started working with a group of people (at a restaurant, no less) who asked me real questions about what I believed because they wanted to get to know me, why I wouldn't sing that stupid knock-off birthday song. I wanted to give them REAL answers rather than the ones parroted from raised-hand answers during Watchtowers, and...
I couldn't. I started thinking about how the world looked from outside a Kingdom Hall. The people I was meeting who weren't harlots and scoundrels who just wanted to see me fail. I remember a moment in class where I glanced at a U.S. map and noticed that the population of the state I live in was almost exactly the total number of Witnesses that year. And I got overwhelmed by the rest of the map. I had never left that state (figuratively). I was never going to. How could I possibly think that the rest of the world was out to get me?
Once I started falling away, the elders inadvertently helped push me. They used pretty scummy tactics to get me to crawl back for the sake of someone I cared about, rather than trying to answer any of my intellectual questions I was beginning to raise. That was a last straw to make me stop going, but it wasn't the cause of anything, even if that's how it ended up looking. Then I found out about things that the organization has changed along their history, and any lingering doubts about needing to go back evaporated.
This got long, but I'm just trying to relay how it feels to be between those worlds and not know where you belong. And that seems like where he is. That text means he doesn't believe he's in any danger outside of the JW world. I don't really think so, either. It's possible he's gotten mixed up with people who are bad influences and have gotten him into drugs or crime, but it's just as possible he's started meeting perfectly moral people who have allowed him figure out that the religion was never really a part of his true worldview. We do exist outside of the organization. I've never smoked, I'm married with the only partner I've ever had.
Last note: My mother still talks to me. It's hard for her, sometimes she tells me how badly she wants me to come back, but she loves me enough that she keeps me in her life despite what the religion tells her to do, because she knows I'm a good person. You can reach out to him. He's still the brother you knew. But you have to understand that you're can't just do it because you want him to live a life he doesn't believe in, but because you love him and you want him in your life.