Public Use aircraft is a function of US statute and not the FARs or FAA. The AC you posted references that law. So in reality there is zero oversight by the FAA. One doesn't even need a pilots certificate to operate Public aircraft except in specific controlled air space per Part 91. However, most PAO entities do follow the basics when it comes to general ops and maintenance but it is voluntary and not regulatory. Outside of public owned aircraft, there are a number of private operators who have mixed operations: Part 91, Part 135, PAO. The AC was developed to assist in those operations and better define PAO since it is not a function of the FAA.