Because he can be so hard headed! I just... he's so restrictive. Don't go here, don't go there. You can't just do this, do that. I'm already old enough to know what's wrong and right, and yet he gets mad at me for being in love with the human world.

It's because something happened years ago that he doesn't want anyone to approach the surface, since apparently people came to Atlantica years ago and messed things up.