The root problem may be that the child has come under the impression (probably from a Protestant friend or relative, since for certain forms of Protestantism, what they call “Confirmation” is their process of “joining the church”) that he has a “choice” in whether to be Confirmed or not. They would get from this the false idea that they are “choosing for themselves whether or not to be Catholic” by choosing whether or not to be Confirmed.
By virtue of his Catholic Baptism, he has to get Confirmed at some point in his life. He has no choice about whether to get Confirmed, and he also has no choice about the fact that he is Catholic.His only choice is whether to be a bad Catholic, or a good Catholic.
However, if he’s not ready to be Confirmed yet (lacks the intellectual capacity to understand the material presented in the process for preparation), then it might be wise to have him wait a year or so before doing it.
Ultimately, it is up to the parents (not the child, not the catechist, not the priest, and not even really the Bishop, although the Bishop has the right to say when and where it will happen) whether to have the child Confirmed, or not, and it sounds here like the parents are choosing to have their child Confirmed.