Odysseus' treatment of his disloyal servants is justified. Odysseus has been loyal his entire life. He cannot imagine anyone being disloyal. In the time of Odysseus, honor was as important as strength and bravery.
Doing the right thing was absolutely the moral thing to do. For Odysseus, loyalty was one of the most important qualities. Odysseus uses his wit to find out who had been disloyal. In a matter of moments, the battle between Odysseus and his disloyal servants is a heated battle. After much bloodshed, Odysseus clears the hall and kills every disloyal servant.
In Homeric times, honor, loyalty and morality was as important, if not more important, as being a great warrior. Odysseus lived by a code of honor. He believed everyone around him should live by a code of honor. To be disloyal would be a crime punishable by death.
That is why Odysseus clears the room of disloyal servants. Since there was no judicial system in place during this time period, Odysseus took matters into his own hands. He stood for honor and loyalty. Those who did not were punished by death. Odysseus was a just man who practiced honor and loyalty. He expected those around him to do the same.