The dealership called the cops. The manager told him that they couldn’t take cash, and that it put him in danger of getting the whole thing seized. The cops were outside before he was through.
He was lucky. They knew of him, and didn’t take the cash. He could have lost it to asset forfeiture, and never seen it again
Hopefully, word about the dealership's snitching tendencies got out on the street, and impacted their bottom line.