I must be missing something here...

Unknown Rabbit, over the space of monthes, loses all his intelligence. Then he becomes a super genius, and leaves the room. After that, instead of seeing what else is on the planet, he goes Back into the room, and assembles a catapault. This shouldn't take too long. Naturally, by the time he's finished, his intelligence is all gone. From the same gas that took monthes when he started with Less intelligence.