2 month old diagnosed with hypertonia. ... could my pediatrician be wrong? could he just be a mover and a shaker?

You mean the baby?: I am not sure if you are referring to the baby or the doctor as the "shaker and a mover?" Perhaps you mean that the baby being a "shaker and mover" is just him & does not represent stiffness, rigidity, or increased tone of his axial musculature. Is that what you meant? If not comfortable with the diagnosis why not ask your doctor to have a pediatric neurologist look at your child?

Hope he is!: Pediatricians are trained to test for infant muscle tone and after having hundreds, if not thousands of normal infants, they should be able to tell if the infants has normal muscle tone. There are several causes for this, including one that is considered transient and benign. Pl follow the advice and get the referral to the specialist.