Odysseus is continuing the slow and deliberate process of returning home and allowing certain people to recognize him so that his return will be on his terms rather than according to someone else's. He knows that the wound that Eurycleia will be cleaning is in a place that she will see the old scar that will prove that he is in fact Odysseus. Even after she sees it and spills all the water in her joy, he makes sure that she will not tell anyone else.
As Odysseus limits all the knowledge of his return, he continues to control the entire process. It is also an interesting section in terms of the narrative process as it is told strictly through the narrator's eyes and also gives us another flashback to the past when Eurycleia served as the nurse to Odysseus and his mother at his birth.