Only someone like Rute, who remembered his hatred every moment and was forever tormented by pain, could continue cooperating with the people of the Despair Tower for the sake of revenge after gaining immense power.
People with a conscience would still feel lost and pained by the blood on their hands, even if they told themselves that every sacrifice served a lofty goal.
Although that might sound like an excuse for him, Rute did, within certain limits, do his best to make up for the harm he had caused others.
For instance, he had actually been monitoring the Hainalson Family and Gilbert all along, but he treated Gilbert himself exceptionally well... he even forbade Aislin and Oliva from encroaching too far on Gilbert's interests.
But if Gilbert really died, Rute would not extend his affection to Gilbert's students simply because he felt guilty toward him.
Of course, he would not abandon the children who had already joined his faction, either.
He would give them everything they were entitled to, but... apprentices who lacked strength and a teacher's protection could not live well just because they were still alive.
The torment of his past had worn Rute's emotional reserves thin. He no longer had the energy to consider so much.
After holding on for so many years and doing so many things, it was already remarkable that these matters could still move him.
One only had to think of those Archmages in Toril who would send even students who had followed them for years to their deaths over mere interests to understand why Hill considered Rute a reasonably decent person.
Yet the more someone resembled Rute, the more terrifying their reaction would be upon discovering that their life had been a joke.
Evil people would not actually break down over everything