What's the squad rule on U23s, I didn't think they needed to be named in your full squad, or at least you can feature a number of U23s without being named in the full squad. (can't remember the exact details...) but AJ isn't really taking the place of an U23 I don't think if that's the case...
As far as I know we can play as many youngsters as we like (someone will no doubt correct me if I'm wrong). The point is, that if we do play the youth ahead of Jahanbakhsh we'll be paying someone top dollar just to fill up a space in the 25 man squad - and we don't have to have all 25 places filled.