I don't know if there is a definitive answer for this question. I can only surmise that the method of the story's delivery (recitation) might make the battle scene with the suitors end abruptly with good reason.
The Odyssey was written long ago, by Homer (who is believed to have been "a blind bard or singer of tales"). Critics consider this epic adventure, in general, to present a wide variety of adventures and themes, and...
the Odyssey is...famous for its use of symbolism and for the pace and variety of its action.
It is difficult to be sure when Homer wrote The Odyssey, a sequel to The Iliad, but both are believed to have been recited in their entirety during a religious festival for Athena, an event called the Great Panathenaia.
With this in mind, remember the length of The Odyssey. It would have taken a well-rehearsed bard (storyteller) to recite the entire poem. Tales told from memory were shared in what is referred to as "the oral tradition." It was in this way that stories and histories of entire cultures were passed down to succeeding generations. Because it was recited, the timing of the delivery of the details may be responsible for ending a rousing portion of the story so abruptly.
In the interest of timing, an effective pacing of the each element of The Odyssey would only add to the overall excitement and satisfaction enjoyed by the audience as it would have listened enrapt, mesmerized, by such a heroic and glorious collection of tales. For example, to create suspense a storyteller would lower his voice and speak slowly. To create excitement, the voice would be loud, words clipped, and the action of the story would move along briskly, leading to a startling climax. An abrupt ending of this segment of the tale could also heighten a sense of anticipation by the audience.
A sudden end to a greatly anticipated act of vengeance delivered by Odysseus (as well as Telemachus and Eumaeus) against the suitors might have been a storytelling tactic on Homer's part to quickly bring his already roused audience swiftly along to Odysseus' reunion with Penelope. Our hero has been gone for twenty-years, feared dead by many, including his wife— though she refuses the attention of suitors on the slim chance that Odysseus may return. The swift ending of the battle scene might startle and surprise the listener as the conclusion of the story comes closer. For all of the different human emotions and behaviors exemplified by our hero by Homer, returning him to a woman he still passionately loves, who returns his feelings, provides yet another side of this larger-than-life hero, providing the character with a well-rounded persona.
In Homer's time, there were no televisions, no computers, no novels, and no movies. The day began with the dawning of the sun and continued only after dark if candles or oil lamps were available. Entertainment would have been rare after dark—except for storytelling, and this would have been entertainment at its best.