In my game, talking to Rooter in that room only has Ace pick up his head and the headless rooter walks around the room in circles.
Good to know my thinking was on the right track..
Rather than the hand icon use the talk icon.
I eventually got it working. The talk icon was telling me we couldn't do it here because we didn't want to wake up the janitor. Then all of a sudden it didn't do that..
