Belmont doesn’t show up in the Alliance version of the Darkshore Warfront proper at all. Nor does he show up on Darkshore when the Alliance is holding it for world quests. This implies to me that the Horde version of the Darkshore Warfront happens directly after the introductory questing - this would also explain how the Alliance had held Bashal’Aran in the introductory questing, but when the Alliance does the Darkshore Warfront proper the Horde is holding it. And that any cycling of the Darkshore Warfront is just for gameplay purposes. Additionally:
Of course, one can assume instead that Belmont is just getting himself captured over and over again off-screen and the Night Elves are able to cleanse Ivus of the blight over and over again as many times as the Horde plagues him with it. But over all that just looks like gameplay to me.