"The Cyclopes have no council meetings, no code of law, but live in echoing caves on the mountain slopes, and each man lays down the law to his wives and children, and disregards his neighbours." (A.S. Kline translation).
In Odyssey 9, Odysseus relates his adventures in the land of the Cyclopes. One of the major themes in the Odyssey is hospitality (Greek: xenia), and the Cyclopes provide examples of how not to treat one's guests, especially since one of the Cyclopes, Polyphemus, nds up eating several of Odysseus' men.
Given Odysseus' horrific experience at the hands of the Cyclops Polyphemus, we should note that when Odysseus relates his story, he is a guest in the land of the Phaeacians. So, on one hand, he may want to remind his hosts of the necessity of treating guests in the proper way.
On the other hand, Odysseus, as a "good" storyteller, may mention the Cyclopes' way of life because he wants to prepare his audience for the inhospitable behavior that he will receive at their hands. He wants his audience to know that he was not dealing with a civilized race of beings.