Paul should has to go through anger management classes of some type and apologize formally to customers.
Showing abusive behavior towards to customers, not expectable. I know this kind of culture come from the top otherwise he would treated customers to professionally.
He was trying to work the register and help process customers. Register was stop. He was very rude instead explanation professional ask customers move to next register.
He need Someone tell Him to explanation a customers professional ask customers move to next register with civility.