Myth or ledgen? I'm not sure what the difference is... even if you meant "legend." But there is a difference between aged and fermented. And, I would never put 100% assurance on the words of Greg Pease, whom I hold in high regards. I just don't deem him the highest authority on tobaccos. I respect the hell out of him, and he probably knows shot loads more than me, but I am not even sure what context these words play from. But...
There are lots of different burleys. And, the differences between Varieties that we pipesmokers call Virginias and burleys is merely marketing. In books regarding the actual botanical aspect of tobacco, there are no differences. It is fair to say that there is "more" sugars in "Virginias," but to say that there is none at all in burleys is probably not 100% accurate. I can pull some sweetness out of some varieties of burley, that I know has not been cased.
If you look at the discovery of "flue curing" what later became deemed "bright leaf" and then marketed to pipemokers as "Virginias" was a burley cultivated in the worst soils know to agriculture, the Virginia and Carolina lowlands, sandy and nutrient deprived. It was accidental that this poorly cultivated burley was made sweeter by turning the starches to sugars with heat. Many in the tobacco farming side, don't even consider there to be any differences between these new cultivars.