I don't think its insane. Goods made in China, Walmart must plan its stores, must plan an area for the Anker area and shelves size and stock, to do that Anker has to commit to a certain minimum guaranteed supply. That may then mean Walmart get the first shipment, and then if they sell well then Walmart get a re-supply.
I then see mention of prices. $10 lower for the Pro online than in Walmart. Walmart won't like that. Can you imagine, go into Walmart, play with the Anker speaker, check your phone, see it $10 lower cost online, then order online and wait.