If he's telling the truth, then his nose will grow, which means he's lying. Telling the truth also causes a paradox.

As a fun side note, he's omnipotent, because if he says, "Either my nose will grow, or I will become a real boy," he has to become a real boy, or it will start a paradox. He could also replace "or I will become a real boy" with any other statement, and that statement must become true, essentially making him omnipotent.