Why should Traxxas re-badge the Castle ESC and motor? It's not their design, and Traxxas won't be supporting the system either. The Velineon was their product, so that's obviously different. IMO, it's a good deal; Castle will get promoted, as well as Traxxas themselves.
Think of it as more of a combo than a new product.
I could be wrong but isn't it just a 7L with a screw on end bell?
Nope, it's some kind of custom-spec'd motor; rotor's somewhere between an S-can and L-can in size. But that's what I meant. The ESC was built by Traxxas, and the motor was specified by Traxxas for Feigao to make.