Actually if you read that link carefully - complete (or even complex) nematode behavior has never been simulated. Different teams have simulated different traits of behavior such as reaction to pokes on the head, non-spontaneous sinusoidal locomotion (there are different kinds of nematode locomotion triggered by the viscosity of the environment). Nothing resembling a learning nematode, indistinguishable from the real thing in terms of behavior, has ever been achieved (unfortunately).