Final answer:
Odysseus prevents Telemachus from stringing the bow to ensure that he alone can do so, as part of his plan to reveal his identity and reclaim his throne in Ithaca.
Step-by-step explanation:
Odysseus does not allow Telemachus to string the bow because the bow-stringing contest is a ruse devised by Odysseus to reveal his identity and reclaim his throne. He had been away from his homeland of Ithaca for 20 years due to the Trojan War and the challenges he faced on his journey back, as told in Homer's epic poem, The Odyssey. By preventing Telemachus from stringing the bow, Odysseus ensures that only he can accomplish the feat, thereby demonstrating his identity and capability to the suitors and others present. This moment serves as the climax of his strategic plan to regain control over his kingdom.