“Who's making all that noise???”
Already sleeping restlessly due to the sudden rotation of the planet by Arcadia centuries ago, Chooloo has been roused from its eons-long nap by the sudden stop. The planet destroyer is still a growing child and needs its sleep, and is now EXTREMELY annoyed.
Whether Chooloo usurps Lord Fang to keep the world permanently locked in night (some quiet at last), or joins the Heroes to start it spinning again (kind of like a gentle rocking motion, very soothing) will be up to you! It doesn't matter much to Chooloo, it just wants to get back to sleep so as to be nice and fresh for the end times.