I think this episode explored the different kinds parent-child relationships. For me, Zombie Kid is a story more for parents than kids because it shows that parents can sacrifice a lot for their kids but not realise that what a child really wants from a parent is acceptance. Be it Gi Do, Moon Young or Kang Tae, all wanted acceptance from their parents and the lack of it has really shaped their adulthood. This is most acute in the case of Kang Tae. Being told that the sole reason for his existence is to take care of someone else would have been really damaging for his self esteem. This seems to explain why he doesn’t really care much about himself. He isn’t shown to have anything he likes for himself. He doesn’t really have any hobbies or things he wants to do.