"The issue is their policy, and their lack of flexibility."
It may not be all their fault.
In some states, sleep products cannot be re-sold as "new." Some industries and some products and some companies are very strict about this (health laws or something). If it had been an ice axe or a stove, they might not have blinked an eye.
Don't take this personally, but a sleeping bag customer could have lice and then transferred that to the sleeping bag.
If a company sells a product like this to a customer, and then if the customer returns it, for whatever reason, then that product can not be re-sold as "new" and it becomes "B stock" and can be sold again as "demo product" or something like that, typically "as-is."
Some companies are a little too flexible in this regard, so if they take back a product, it will be transferred to the "B stock room." Then by some miracle, a "new?" product exactly like it comes out and is sold again to the next unsuspecting customer. In some states and with some products, the company can get its hands slapped if caught doing this, especially if the product has a serial number.
–B.G.–