I am moving today and tomorrow but wanted to check in on this thread. Your son should do a music supplement with recordings or videos, music supplement (including the info posted here), and letters of recommendation (1-2) related to music. This can make a lot of difference with admissions and I think he can shoot high. Many schools (including Harvard) have broadened their curricula to increase access and diversity so although there may be a strictly classical path available to those who want one, there are other ways to go while majoring in music.
A general music BA sounds good for him and will include theory, composition, music history, ethnomusicology, technology etc. Often funded lessons sometimes for credit, and extracurricular performance. Also studio/music tech classes and access to those resources.
I personally know the Tufts music department and the composition chair and it would be a great fit if financially feasible.
Clark University has a really interesting music curriculum and has produced some talented composers. (Worcester MA).
Oberlin has a Musical Studies BA.
He could consider Ivies and little Ivies with great financial aid if his music supplement is submitted. Harvard, Yale, Princeton, Columbia (is on there), Brown and also Amherst, Willams,Wesleyan (Tufts is also a little Ivy). These schools will also appreciate that he has many academic interests and they will enrich his muci.
I am intentionally avoiding schools with BM programs (except for Oberlin). Bard, Oberlin and Lawrence are often mentioned for double degrees for kids with multiple interests, as well as Harvard /NEC and Yale.
If he is more interested in commercial music or music production, music tech. etc. I will PM you with a list of schools for that. It sounds like he is working on a DAWS… Does he make scores?
More after my move!