The lower planes were a lawless sort of place, not because they valued independence, but because the vast majority of the population lacked any instincts except to kill and torture. The need for food, for shelter, for water, those were all alien to them. All they knew was death and suffering.
Of the beings here that did have some sort of true intelligence, all were very much the same, with a small sense of community born of allegiance to a more powerful being added on.
So, as Wolfe fought with the Trolls, they didn't care who was winning, they didn't care why he was even there. What they cared about was that he was there, and that he was absolutely brilliant at making others suffer.
In their minds, the subjugation of the undead was the most amazing piece of magic they had seen in centuries, able to steal the freedom of other beings and bind them to yourself to the point they could not betray your will.