I'm just saying that that's what he's told everyone else. He made it very clear that he wanted magic to be unique and legendary, not commonplace. Plus being an island isn't only a downside. First of all, that's a big island and it'd be very hard to completely blockade it. Not to mention that people have to load their armies on boats in order to get there in the first place.

And guys, don't start discussing what you're going to do with the nation of the guy who left. I don't see any reason to make it an NPC instead of just saying it doesn't exist.