I thought he was saying it was less maternal and more how they are her possession/agency in the world. (i.e., less about Joffrey being king, and more about HER SON being king.)
Parents who treat their kids as extensions of themselves aren't really that paternal or maternal. Paternal and maternal parents take joy in their children's joys, mourn in their losses, and invest in their kids without expecting return; Cersie seems to live through her kids because she hates her life. How much does she actually love THEM vs just love that they are hers? I'm not sure.