Calvin wanted this high return business for himself. And the fact that Luther family was going to take over the business after the fall of the Sosis family was a hindrance to his wishes. He wanted to monopolize the whole business by taking over the forestry and the exclusive mining rights for the place no matter what.
Therefore, he didn't plan on bothering to play the good guy in front of the Luther family and had already considered them his enemies. Of course the fact that Zach was a dark mage also helped him make up his mind in choosing this method.
After carefully thinking about the whole situation and coming up with various alternatives to the situation, Calvin decided on his course of action. But he needed to discuss this with someone else; someone who was like-minded and would be able to give him the right advice as well.
