Harold was rightly pissed off that flavorful, wild salmon was only available frozen (freezing depletes flavor and texture). The only fresh salmon was the farmed stuff - bland and uninspiring - but he bought it, opting for fresh over frozen. But why didn't he and Lee Anne cruise the fishmonger and choose something both fresh and flavorful, and then rewrite the dish? I am sure that the Scotts would have been OK with a change in the menu, if it made for a superior dish. In the end, Harold's farmed salmon - already bland to begin with - was pre-cooked (due to time panic) and didn't integrate with his green papaya salad. A solution as simple as poaching the fish in a nage of green-papaya vinaigrette would have taken the same amount of time, would have imbued the fish with some additional flavor, and allowed it to stay moist.
Stephen was painstakingly slow in making the dumplings, thus becoming useless to the rest of the team. This illustrates an important point - It's getting it done perfectly, consistently, in the allotted time that takes talent. Frankly, I think Stephen lacks the experience to be both excellent and fast, and tells himself his attention to detail is evidence of higher standards. Worst of all, Stephen designated himself the Service Director for the evening, and wasn't even around to put out his own dish.
As for the cake mix... Initially I was surprised to see boxes of the stuff, but frankly, it didn't trouble me. None of the chefs are bakers and white cake is white cake. A mix allowed them to turn out a decent product in a short amount of time. I wouldn't advocate this in other areas - say, substituting prepared food from a deli case for freshly made - but in this case I thought it made sense, since they still had to create fondant, buttercream, etc. to flavor and decorate the cake - and this is where the real skill lies.