He got up, bc he was going to head a live mic. (Experience from his decades in radio, tv, and Hollywood. "ohh this mic is dead, let me go over to the other one on stage :) Also to prevent feedback/noise pickups, you turn the existing mic off at the base, when away from it, so it doesn't interupt you at the other mic (even if it's on/off at the other end of the mic cable.)