So sorry to hear about this TMC. It makes sense that any protective parts would be very present, vocal, and defensive after such a frightening thing.

Is C willing to try to learn? If he seems like a good T in other respects, perhaps simply reading a couple of books would go a long way toward helping him understand. Many therapists do seek additional education or training along the way, and perhaps he'd be willing to do this, at least informally. I think Internal Family Systems would be helpful for many clients, for instance.