Well, when he extracted Claire's powers, he didn't want to kill her for some reason ( could it possibly be that he thought she was too cool?
) If so, he couldn't possibly wanna kill superawesomepwnage Mister Spock, and just wanted the power of logic!
SO true! He and Spock would be fabulous together. They could rule the universe together. *pauses to ponder on that imagery* And it would be hot.