"Thus" ...that implies that businesses have no legal protection when they buy stuff, which would, for example, spell doom for all retailers who are businesses who buy everything they sell on to consumers who have rights that they don't?
They have enough negotiating leverage to work out specific deals with suppliers for how to deal with returns. So for example, Walmart will be able to send back returned stuff to the manufacturer because that's the deal they work out.
Anyway, non-lawyers really shouldn't be trying to do legal analysis. You'd need to a lawyer based in Sweeden to tell you the legality of that T&C. Speculating about it is just a waste of time really.