Since it is the spring schedule he’s wanting to change, I’d let it ride until after school starts in the fall and then put in the request.
Lots of kids take more courses in the areas they like. Look how many kids on CC take not only 4 science classes but 6, or the traditional math courses plus statistics and calc (or several layers of calc. The only caution I’d give is taking too many classes that require a lot of reading. I transferred schools as a senior in high school and was like a kid in a candy store with a course catalog rivaling some colleges(old school had a couple of college prep level courses, but everything else was just basic) and I signed up for 2 literature classes and a senior seminar that all required about a book a week. Too much reading!