As a "business strategy", this one would suck. If the purpose of this strategy is to drive prices up, then it fails because retail prices aren't being raised. It fails twice as much when you consider that "hoarding" of this ammo in warehouses costs money. Money which, evidently, isn't being recouped by higher prices.
And let's assume this "major retailer" you're not divulging the name of is Walmart. Walmart has over 3,000 super centers in the U.S. Assuming 4 million rounds per store (an average of the 3-5 you cited), that would be 12 billion rounds hoarded. That's about 2.5 YEARS of total annual production of .22LR in the U.S.
Assuming it's Academy you're talking about, there are 138 stores. That adds up to 552 million rounds. Which would mean you'd be telling us that a chain that sold $3.7 billion in retail goods last year is intentionally paying storage space to sit on half a billion rounds of .22LR ammunition?
Assuming it's Cabela's, there are about 50 or so. That adds up to 200 million rounds hoarded for a sporting goods store with a booming ammunition sales section. Doesn't seem like good business to me to pay storage for "hoarding" something they could be selling.
If you've got something to put out, then put it out, give us something to investigate on our own, and be done with it. Otherwise, it's all baseless hearsay.