“My understanding is that the Code has never been formally adopted into law or accepted as an ethical standard by any medical association.”
Neither has the Hippocratic oath been formally adopted into law, but it is a bedrock of medical ethics. Both are referenced in medical malpractice trials.
A lot of things are referenced in medical malpractice trials. Which of those things are based on actual points of law? And even if this is true, then this line from your letter seems like it's verifiable B.S. anyway:
... implements the internationally agreed legal requirement of Informed Consent established in the Nuremberg Code of 1947.
What "legal requirement" is this?
Anyone who is in a position like this needs to understand that you're not sending this letter to some anonymous jackass on the internet, or some random guy stocking shelves at Trader Joe's. The letter is going to end up in the hands of a corporate attorney who may read it and then advise the company to fire anyone who would put such a clear demonstration of his ignorance in writing.