What are the odds the friend is actually 14?
Am I the Asshole?
A catharsis for the frustrated moral philosopher in all of us, and a place to finally find out if you were wrong in an argument that's been...
In my opinion, he's the asshole for pushing. That said, if you've been talking for a year, I think he's just trying to learn more about you and doing it wrong, not that he's got some scam behind the scenes. But whether he's real or not, a friend should respect your boundaries for something like this, it's literally a safety issue, and he's being a bad friend.
If you value this friendship and think this can be a one-time thing, I'd unblock him and give him another chance to leave the address thing alone. If you don't think he's real or don't think he'll leave it alone, leave him blocked, and either way, he's the asshole, not you.