I bought a Solo stove from Walmart for $75 a couple years ago. I thought it was an accessory or something, but no it was the actual stove. A manager was ringing it up because even the cashier thought something was fishy.
The manager said that what happens occasionally, is that someone will order something online from Walmart dot com, then the customer will refuse delivery. It'll sit on the truck until it comes to a walmart and they dump it off with all their other stuff. Since it's not in their inventory and there isn't a way for them to send it back, they'll just accept it and sell it at a discounted price. As far as Walmart is concerned, they still made $75 on something not inventoried.
This has happened a couple other times in the past, like a grill I got at Home Desperate that they didn't sell, or finding Ozark Trail stuff at the REI garage sales.
I think they did a terrible job explaining to you this was a one-off sale, and you probably should have contacted Samsung for the warranty instead, but I don't think you did anything differently than I would have done either given the information you didn't have at the time.