I've said this before, but what makes Kosgei so impressive is his range and ability in events from 800 on the track to 8k in xc. Your post states that Yuot and Moen were two "of the greatest, if not the greatest, DIII xc runners" of all time and specifically you point out Moen's 24:30 at Hanover's course.
I'll be the first to agree that Moen and Yuot were sensational DIII runners but I do not think either of them are anywhere near the level of Kosgei. Moen graduated a 5 time national champion...Kosgei has done that in two years. And yuot and moen both posted some sick 5k and 10k times, but they really don't have a fraction of his speed.
My point is simple, to say that Kosgei "can't" win by 40-60 seconds is really not giving the guy credit. He'll do as he pleases at nationals.