After the blue rinse is over, why is Butler angry with Artemis?

Butler is confused when he first awakens after Artemis has drugged him. Once he realizes where he is, he demands that Artemis explain. Even after he does so, Butler is still upset because he realizes that Artemis took a big risk with their lives even if Artemis does not see it that way. Butler is also worried for Juliet who has not yet awoken.