Mettaton may as well have been EX'd out, because with the way he moves, you can sense that he would be stomping towards Kaworu if he didn't have just a wheel for locomotion. So instead he angrily rolls up to the boy, his screen--or at least the squares that were still functional--a solid wall of red.

"Because while you are correct that I was interested in conversation, I am NOT interested in having a child attempt to psychoanalyze me, and then have the nerve to leave!! I was talking to you, and it is RUDE to simply leave a conversation without even a hello or goodbye after dropping your judgments!!

Learn some manners!!! I did not treat you unkindly until this point!!"