Because he is sixteen, he is pushing for a first-team place ahead of Digne, and he is not, in fact, Rooney.
I agree that he should probably move. This is not best for the club, but it's best for him.
Refusing to come to training is egotistical. He is sixteen. He has not done enough to be entitled to hold out for a move. He should be glad we're willing to give him a professional contract on the day he becomes eligible.
If he doesn't want to do that here, he should do it the right way. Show up for training. Pass on our contract. See if we move him, or if we let him go on a free next summer. I bet we move him, because something and a 25% sell-on is better than nothing.