Polar Aviation
Sorry for the delayed response, I haven't visited this thread for some time.
Re the question: "Why didn't he just do what CASA wanted him to do" or words to that effect:
I think Clark was concerned (as many others are) that compliance with the requirements of this particular individual were either dangerous to the pilots or carried an unacceptably high risk of unnecessary damage to engines due to shock cooling, all without any safety plus-side at all.