You misread. There were three people jerking the Earth out of orbit. The mass of the moon is far, far less than 1/3 the mass of the Earth.
(And compared to the exertion of jerking the Earth around, absolutely nothing Clark has ever done on a daily basis is any kind of exercise. That's like saying picking up and carrying individual pencils is legit exertion for somebody who can hoist a loaded twelve-axle shipping truck over his head.)