They calculated that Pence would be a traitor because he is a traitor, and he did the traitorous thing they knew he would do. So, he was part of the plan and unknowingly served his role. It doesn't make him good. Judas is actually a perfect comparison because Christ knew that Judas would betray him before Judas knew he would. Yet, it had to happen that way in order to complete the plan.

They calculated that Pence would be a traitor because he is a traitor, and he did the traitorous thing they knew he would do. So, he was part of the plan and unknowingly served his role. It doesn't make him good. I don't know how much more clear I can make it for you.