Actually, I really thought RB made the right decision. The JJ/James combination strikes me as far more likely to be succesful restauranteurs Chris & Nathan. A restaurant is a business, after all. I haven't actually watched previous series, but as I understood it, the premise of the programme was to find some ambitious talent for the judges to go into business with - with all that entails.
Chris was a competent cook, certainly, but not spectacular, and competent cooks are dime a dozen. Nathan, on the other hand, was diabolically bad as a FOH person, and surely no amount of training could entirely undo his contitutional bad attitude, or erase that perpetual sneer from his face. All IMO, of course.
I did feel for Chris, but ultimately JJ and James had more potential, more charisma, more ideas, and seem far more likely to succeed.