It's how the world works.
If they get out of date or out of season without being sold and they were given away for free, then people considering buying it would not buy it, and wait it out until they were given away for free. So they can't be given away.
Low cost goods, magazines, books, newspapers and seasonal items normally operate in this manor, as returns and freight cost and shelf life is more than what the product is worth.
Why aji joe and why the CVS employee shouldn't give them away is because it would be fraud. Producers don't often want the old goods shipped to them because they are useless for resale and it would be a waste of money and transport costs, so they give the retailer the benefit of taking them off the market and making them disappear, ie pretend they were returned without the hassle, retailers get reimbursed for unsold 'returned' stock. If those products are given away then it ruins that process, breaks the cycle that makes that system work without freight costs.
So by getting free seeds, the producer is ripped off (gets nothing from the sale and has to reimburse the retailers for the privilege), the retailer fraudulently claims seeds were destroyed to the producer but didn't take them off the market.