So how does the seller get his funds if the buyer refuses to release in this situation? That's what breaks your logic. And yes it would be nice to have people that are honest and all. But a scammer in this situation would talk you into that logic.
I think the the buyer can refuse to release the funds only in one situation, if he
is oligophrenic person with defective brain (like some subjects here) has a problem with logic, because in this situation he can lose
twice more coins than the seller.