Depends on your definition of “open”. If you don’t want to take a foreign language, you don’t have to. If you don’t want to take a lab science, OK. There are so many classes in each division that it’s hard not to find something you’re interested in, and one of those three courses can apply to your major (so that leaves only two). If you’re double-majoring in two of the divisions, you only need 3 other courses.
And for the OP’s son, interested in so many things, completing the clusters should be no issue.