Where I live a cord of wood has a bunch of different meanings, depending on conditions; a few firewood guys sell wood split, delivered, and stacked...the pile may be 128 cu ft, but they can get 127 cu ft of air between them sticks...
I aint never seen an oak tree big enough to have that much wood in it, I can't judge. My first inclination is that there's something fishy with the whole story about the tree and about the saw.
If I had never cut a tree down in my life, why would I buy a $700 (more or less) chain saw to cut one down? What dealer would sell a new pro-level saw to a rookie like that, for a purpose like that with charging him an extra $10,000 for an insurance policy? If the tree was that big, it might have required a permit to remove...the guy was from California, wasn't he? In some cases out there, the permit also requires that the owner either prove he has the equipment and skills to do the job safely, or hire someone who does.
And then again, maybe we are dealing with a dot-com millionaire who used to have more $$$ than sense.