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.