Earlier quoted context omitted.
Change of ownership happens at the point of sale. Toss them a cheery "no, thanks," and walk on by. They have no authority to detain you. Same with Fry's. Not the same with Costco; there, you're subject to the membership agreements.
They do have the authority to prevent you from returning to the store. This is the only reason I ever agreed at Fry’s. At Best Buy I stopped shopping there for years. I don’t remember why I eventually went in one again, but in the years since I’ve never been asked once. I do wish they’d get rid of the guy at the door entirely. It’s weird. And they always greet you from the side or back.
Sounds like a good reason to show your receipt... at the returns counter.