I did say something in writing would be best in my first post.
I also suggested he start by calling. If he lays it out they should be able to make recommendations or tell him what he needs to submit to them, and to whom.
Going in and meeting with agents face to face is not "inappropriate" or "unhelpful"; on the contrary. These people do still work for us after all and your post IMO contributes to the OP's impression that these people are unapproachable: "Never heard of a Federal Gov Agency being that accommodating on a personal basis!" is what he said. I believe dealing with something on a personal contact basis can sometimes help expedite things.
Also, you use the terms "formal opinion", "legal opinion" and "legal ruling." What exactly is a letter from an agency attorney going to be in this case?