Humidity is the biggest culprit when it comes to the degradation of paper over time. No matter how light tight the container, humidity will creep into the emulsion over time. I am not sure why it effects it, whether it begins a chemical reaction with the emulsion or greatly increases the speed so a chemical fog is the result when used.
The logic behind freezing is that a very cold freezer, a deep freeze type that does not have defrost cycles will keep the humidity near 0%. If the emulsion just breaks down over time, the sub-zero temp will retard this as well.
Unless you are the one freezing the paper, I don't know what to expect from someone else. I suggest you buy the smallest quantity possible and run some tests to determine its quality before buying a large lot.
"Fundamentally I think we need to rediscover a non-ironic world"
I recently make some 16x20 prints on Oriental Seagull graded paper that had been stored in the freezer since summer of 1995. Since the power had gone out on the freezer once, and the paper had been exposed to a rather wet defrosting, I was going to toss it, but then said, "what the heck, I'll give it a try". To my surprise, not only was the paper still in good shape, the prints made on it were indistinguishable from prints made on new paper of the same brand. The paper was partially used, but sealed with box tape in the maufacturer's lightproof plastic bag and in the cardboard box, much like it comes from the factory. I would imagine that an unopened box would still be in perfect shape. The danger with older paper is fogging, which can be combatted somewhat by adding a restrainer to the developer (KBr or Benzotiazole) if needed. Unless the paper is years old, I imagine this would not be a problem. Good luck.