You gotta think of it like this: Calus is the exiled emperor of the Cabal, which are normally fiercely loyal to one another. He treated being king like a game show, rigging coliseum games in his favor with his buddies, he castrated Ghaul's "Consul" buddy, and is only using us as pawns in the long game, likely to take back the empire. I doubt his intentions are completely rooted in the goodness of his heart.

<But he tried to free the Psions.>