That's beside the point.
They are saying that if your Messages app uses the font and other visual cues to simulate the appearance of a genuine message, your app will not be approved for sale in the Messages app store.
But I think Apple does own the copyright to that font.
[doublepost=1475268145][/doublepost]
How are you going to stop them? They can pull the app from their store. What are you planning to do to dictate what they sell in their store? How dictatorial do you want to be?
If you want your friends to send you messages calling you smart, you should negotiate that with your friends.