Taking into account the statement above: "How might Menelaus' story about the Old Man of the Sea, Proteus, be instructive to Telemachus in his quest to find his father? Why, for that matter, would Menelaus' response to the knowledge Proteus gives him be instructive for Odysseus?"
The answer is: He could find the Old Man of the Sea; also now knows that his father was still alive during that conversation.
Hope this helps.
