I will second, or third, or fourth or whatever ... that you give him Crisis of Conscience as a gift.
Ray's tone in that book is very loving and concerned ... its a great book. My sister was in a kind of similar situation - disfellowshipped, but still believed it was the truth ... though she did have some doubts too. I recommended she read CoC and now she is free, and her mental illness is a thousand times better.
Same thing with my father. CoC set him free too. And I personally think it is the best book to read, because Ray lets you out gently, he doesn't send you into a fiery rage against the org and everyone in it - you come out with more love and a level head. Hopefully it can do the same for your new acquaintance, and hopefully new friend.