Sounds to me like this is a gun shop that isn’t adverse to selling under the table to the criminal element. All the article said was that they sold to someone who, by a unconstitutional law, they were not supposed to. If they had actually done a sale without the check then they would be in jail. The feds do not allow that to happen.
Who are you kidding? It happens all the time. There are shops that are directly related to organized crime, street gangs, and a host of unsavory elements. Gun shops are like everything else. There are good, honest shops, and there are corrupt shops that deal primarily in black market weapons.