OpenBazaar is a network of individuals running the software on their local computers in order to engage in trade with others directly. The network is peer to peer, with one computer connecting directly to another. It isn't controlled by any individual or organization, including the OpenBazaar core developers. As such, no one allows trade to occur, and no one can prevent trade from occurring except for law enforcement.
The developers of OpenBazaar (or any other organizations) have no control over listings or other users on the network.
OpenBazaar only provides the software necessary to create a store, list items, and purchase items from others. Therefore, the use of the OpenBazaar software and network is at your own risk. The developers of OpenBazaar can not be held responsible for any of your trades. We encourage OpenBazaar users to use the platform in accordance with the applicable laws in their relevant jurisdictions and in accordance with some common sense.