A man of color......"complexion" is defined as being the "natural skin tone" of an individual, this is before any exposure to sun and weather, which is why your author made reference to "as if" instead of "was", and then went on to explain that upon his second return Beale was even "darker then ever" which is to say that he was already dark even before any exposure to sun and weather.
We know for a fact that Thomas J. Beale of Richmond was a free man of color and we understand the limited ways in which men of color could have been either emancipated or born as free men throughout the period, etc. We are also told by the author that he felt that Beale was from some "western portion" of the state, this being in "1817-1822" to which at that time all of the Virginia's were still just one Virginia and governed by the same laws, this however, not being the case after 1863. It's important to remember that the narration was written many years after the events and not during the events as we might expect with a journal or diary. So, in essence, several years after 1817-1822 a man sits down to author a history as best he can within the various limitations imposed on him. This individual has the ciphers, the letters, and the history behind the events in question and during his narration he has provided inaccurate details about the source of the wealth and the manner in which the ciphers were numbered, this last fact insuring that he and the original coder, at the very least, "shared the same knowledge." So, what is the only remaining scenario in which this could be possible if the author is indeed narrating a somewhat altered but true history? Answer - the author had to have known the original coder. PERIOD! All of this is what caused the author of this new theory to ask the right questions and then continue to look for the required proof.