Why does Athena mention Orestes to Telelmachus?

Athena reminds to Telelmachus about glories history of Orestes. She tells him No matter how far out of the world you live, you will have heard of Agamemnon and the bad end he came to at the hands of Aegisthus- and a fearful reckoning did Aegisthus presently pay. See what a good thing it is for a man to leave a son behind him to do as Orestes did, who killed false Aegisthus the murderer of his noble father. You too, then- for you are a tall, smart-looking fellow- show your mettle and make yourself a name in story.”. This way she is comparing two young men and inspires Telelmachus not to give up. Also Telelmachus finds out from Athene  that meanwhile Aegisthus here at home plotted his evil deed. For seven years after he had killed Agamemnon he ruled in Mycene, and the people were obedient under him, but in the eighth year Orestes came back from Athens to be his bane, and killed the murderer of his father. Then he celebrated the funeral rites of his mother and of false Aegisthus by a banquet to the people of Argos, and  on that very day Menelaus came home, with as much treasure as his ships could carry.