Actually he doesn't. Although they both call themsleves NDs, you need to research about the history of naturopathy and how the field was splintered into 2 philosophies (the traditional naturopath and the naturopathic physician). It is an interesting debate, one that I have not yet made up my mind on yet. I tend to think in this era both are needed and can/should be allowed to practice.
Sometimes the best healers in the world (I know some tremendous Amish ones) have no standarization or credentials so I don't neccesarily agree with your assessment DH is a quack just becuase his training is not recognized. He supposedly trained under Dr. Christopher himself, and I would consider that experience better than any ND accredited medical school residency program.