Bob,
Earlier you mentioned that the author wrote: ..."the [13th]will remind one of the Redan at North Berwick." and you suggested that somehow proves: "It was not a hole unfamiliar to US golfers at the time."
On the other hand, I wonder just how the author knew. You are supposing he had first hand, familiar knowledge, I propose that was he given that information by someone who knew what those holes represented.
There is no way to know who's correct.
As for Moriarty/Wilson, if no conclusion has been reached that he visited N. Berwick, how could he have drawn an unshakeable conclusion as to the merits of the hole without seeing one, or maybe he saw drawings or plans, or perhaps a photo or two, or talked about the hole with others?
I seem to remember that these fellows had some relationship to one another. Even if Wilson already knew about the hole, it's entirely feasible that Macdonald's love of the stratagem may have had an influence on him, and I'm afraid it would be impossible to prove the question either way.
David's posts are one man's premise, and one man's opinion on a particular golf course, not an insinuation that no one in America would have ever known about the great UK holes without him.
I remain unconvinced, but open minded.