While it may be that some private doctors won’t understand some military medical conditions, most will quickly be brought up to speed once they have patients who require their expertise.
There are bad, average, good and great doctors in private practice. Looks like your husband was blessed to find a great one when he ret’d from Vietnam years ago.
I really hope he does implement Newt’s idea. It would be life-changing (for the better) for our dear vets who deserve the best.