May refere to NACE RP-286, the Electrical Isolation of CP Pipelines, for the use of the CP isolation.
IMO, the galvanic anode CP system is the current flowing through the electrolyte. The electrolyte of the buried pipeline is the soil. For the aboveground pipeline section, there is no cathodic protection since the current won't flow in the air. The isolation kit on the aboveground pipe won't be needed.