I think your son made a wise decision about the college calculus and physics classes. In my field, the AP course is something of a joke mainly because there are so few high school teachers who really know the subject. And it rarely hurts to sit through an important subject again, even if much of it is somewhat familiar.
He’s a sensible young man - most of the time. Some of his AP teachers have been excellent, and others not so good. Fortunately, he is astute enough to know the difference and adjust his plans.