I can SO relate to this post, 18 years ago or there abouts, I was that kid your son is friends with. I was raised in the Worldwide Church of God (Herbert W Armstrong), and since learning from this site what JWs are like, I have seen more and more areas where they are both similar. I so hated going home to this environment that I took to going to a friend's house after school instead of riding the bus home. My friend's parents were very understanding, after getting to know me and talking to me they realized that my home situation was pretty untenable. So, they let me hang out with them quite a bit, I was nearly another member of their family, eating dinner at their house, etc.
Once my parents figured out where I was spending my time, and how I was trying to avoid them and their strict religious beliefs, they started complaining to the school principal, calling my surrogate family on the phone and harassing them by making threats of reporting them to the police as having kidnapped me, and other tactics. I think they actually DID call the police on them at one point, my memory is fuzzy on some of the crazy stuff that went on back in those days. At one point, due to the complaints of my father, the school principal pulled me into the office for a talk. He informed me that because of my father's complaints, and certain legal technicalities I was obligated to take the school bus home. He told me that if my home life was that bad, I should call social services, police, etc, but in the mean time, I MUST go home on the bus, once there I was no longer his problem and could do what I wish.
Well, I was a stubborn kid, and I thought that was pretty crappy in the first place, and it was much easier to walk to my friend's house only about a mile from the highschool than it was to get away from my house which was about 6 miles away from town. I kept doing the same thing, and ended up suspended from school for not taking the school bus. The irony here is that adherents of the WCG (and JWs too) were always talking about how corrupt "worldly" organizations like government and school systems were, yet my father used the police and school administration to enforce his will on me.
Anyway, the point of me relating that story is this: be very careful with this situation. Depending on how nutszealous this boy's parents are about their religion, they could become very hostile toward you, and make things very uncomfortable.