You have referred to the Parental Kidnapping Prevention Act as well as certain crimes you refer to as First and Second Degree Custodial Interference. You appear to be confusing apples and oranges, however. The PKPA, 28 USC 1738A, merely specifies under what conditions a state court does or does not have to give full faith and credit to a custody decree from a court in a sister state. It doesn't create a crime, as you suggest.
I am sure you will correct me if I am wrong, but I have looked at Title 18 of the U.S. Code, and there doesn't appear to be a federal crime called "custodial interference". Many states have such a crime, but their definition is different in each.
The closest thing Georga has to what you describe is
this:
"...(2) A person also commits the offense of interstate interference with custody when the person removes a minor or committed person from this state in the lawful exercise of a visitation right and, upon the expiration of the period of lawful visitation, intentionally retains possession of the minor or committed person in another state for the purpose of keeping the minor or committed person away from the individual having lawful custody of the minor or committed person. The offense is deemed to be committed in the county to which the minor or committed person was to have been returned upon expiration of the period of lawful visitation."
That would not prohibit the father from taking the child to another state, provided that he return him upon the expiration of his visitation.