Line Type B item in P4310 PO entry causes error "Item Branch Record does not exist"

Item Master record has been created for a product has Line Type = B.  Need to order this item as direct charge to a project cost code, 

Entry of this item in PO line, with line type = B and an account number, causes error that Item Branch record does not exist.

Why is this validation done when we are purchasing to a business unit and not for stock ?

Creating an Item Branch record is unnecessary and creates considerable data management effort.

Is there a solution to preventing this error ?