In my opinion,calling up a primavera member to first team,letting him train with players who have made it on the big stage and getting some minutes in front of 40000 people will be a better learning experience than playing in the youth squad against youth teams in front of nobody.
Waiting for them to explode hasn't really worked out for us all these years(only good player is Marchisio),so why don't we try to throw them in the deep end of the pool and see what happens.
Worst case-He plays 0 games,gets to be around superstars and goes back in January with more determination to make it,and we are back in the market for another striker in the January transfer window.