One thought I had is that he could take an extra 1 or 2 classes each year online through an accredited online high school program to meet these requirements. However, our high school wouldn’t accept these classes for credit, so they wouldn’t appear on his official transcript. We’d need to send in separate transcripts showing those courses.
Do you know if colleges would accept these courses to meet the requirements? If it makes a difference, he’s probably looking at either less competitive state schools, or smaller less well known liberal arts colleges.