Those that brought up Mudd, Caltech, MIT etc. wasn’t because anyone thought the OP kid went there, only to show that even the most intense STEM schools out there require humanities. But no matter what college or university you go to there are going to be requirements.
OP, your argument is " He studied those subjects in high school. ". Well, he also studied STEM subjects and you find it worthwhile to further his STEM education in college…likewise it’s important to further the study of humanities.