Disregarding the spoiler below. At this point in game it is reactionary because Rook accuses him of using his blood magic and insinuates that Solas is controlling Rook. Which is what he abhors because the Elvenuris used Blood Magic to bind the Ancient elves which he roused a rebellion against. Even in Inquisition Cole asks Solas to bind Cole's spirit using blood magic and Solas was quick to decline. He also states that using Blood Magic weakens his connection to the fade.