Scarne was an arch-exaggerator and self-promoter. I think the one thing that is likely to be true is that Scarne's description bears no relation or clue to the method but rather is a complete fantasy description of the effect. We all know (or should know) that lay people perceive some effects using simple methods as complete miracles. That's because they have no real comprehension of any methods and human recall is imperfect.
I would suggest that Scarne's method would have been pretty simple. The best clue to that assumption is Mike Skinner's relating of having his fantasy of the great John Scarne (the same fantasy that you all clearly share) deflated when he first met him in company with Dai Vernon at the Castle. The passage conveys Skinner's disappointment pretty subtly - he was always pretty diplomatic by all accounts - but I think it's there.
I discovered magic in 1958, after reading John Scarne's autobiography "The Amazing World of John Scarne." In this book he described how he could cut to the four aces in a shuffled deck of cards. Johnny said that he would spot the aces during a riffle shuffle and count how many cards fell on each Ace and later cut to that number.
This description fascinated me and I thought to myself, "I would love to see that performed some day!" Years passed and I moved to Hollywood and the Magic Castle. This was in the summer of 1967. John Scarne arrived at the Castle one night, around 1972. I had the pleasure of joining Dai Vernon and Johhny for dinner that evening.
After dinner, out came a pack of cards. Dai asked Johnny if he would cut to the Aces for me. Johhny was obliging, but he performed an entirely different routine from what I described above. When he was finished, we talked awhile. Then the Professor said, "Mike, knock out the aces for Johnny!"
What the perpetual obsession with this (irrelevant) method amongst magicians shows is the power of the imagination. The story is captivating - Scarne knew that, that's why he wrote it as a self-promotional piece. Bill Malone recognised it as a very compelling hook on which to hang a presentation. I think if you spoke to Malone (assuming he was willing to get into the technicalities of his act) he would be more interested in the whole Scarne myth as theatre, rather than caring about the method. Like the center deal, there are dozens of ways to fake this sort of effect that don't actually involve the onerous task of doing the real work.
As I said above, laymen perceive the effect, not the method. The best magicians have a capacity to put themselves in the shoes of a lay audience - and Bill Malone is a truly great magician.