has he changed the fan relay?
I would start with a 20 dollar coolant temp sensor if it was me. Ive never seen a head gasket go bad on a saturn but it is a alluminum head and anything is possible if it has overheated.
ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL
INSTALLATION IMPORTANT: Tap out sensor mounting hole in engine head to remove thread sealant residue. Clean any sealant residue from old sensor and apply RTV sealant to threads if old sensor is going to be reused.
I replaced the sensor today. The fan kicked on at half hot. Way to go!