This is very nice of you to share. I hope you don’t mind a few rambling comments for the sake of your child and for others reading this thread.
By limiting your search to schools that offer a formal minor in composition or even a minor in general music, I believe you are limiting choices too much. And when you write that most music minors are for performance, you are most likely looking at schools that offer BM programs, not BA, which would not be a good fit unless your son wants a double degree.
You have to be careful not to mix apples and oranges, with a list that has both BA’s offered by music departments and BM’s in composition in music schools and conservatories. They are different programs, with the BM 2/3-3/4 music classes and the BA 1/4-1/3 music (Harvard is actually 1/2). BM’s are immersive and many don’t offer minors.
Most (but not all) schools that have a BA program for music are academic programs that focus on theory, composition, music history, ethnomusicology, technology in music, musicology and so on. There may or may not be a performance component at all. There may not be a specific composition minor but composition is part of the program or permeates theory classes.
It is fairly easy to find a BA program, which is offered at countless schools including liberal arts colleges, that will allow a non-music major to study composition as part of an academic music class.
Some BA programs offer a specific strand in composition (example would be Brown) but the absence of that specific strand may not matter as much as it seems.
A student can study composition privately and take a few classes in theory and composition (or even just theory) and still develop during undergrad years.
It is not necessary to do a formal minor in order to take music classes, at most schools with BA programs. Some departments will offer composition seminars specifically for non-music majors, and some have open composition classes. Classes can be taken as electives. A minor is just a specific constellation of classes and may not be that useful unless every class in the minor curriculum is needed for some reason.
There are many paths that composers can take. You do NOT need a formal minor or a specific strand in composition. You can assume that most any academic music department will be offering some composition to students, whether it is hidden in the curriculum or in plain sight. It is not necessary to major or minor in music to make enough progress with composition to enter grad school. I certainly know a person who studied engineering at MIT but then did grad work in composition. I know young composers who went to conservatory, who are now doing academics and the reverse, students who majored in something else entirely and are now doing doctoral studies in composition.
The long view with composition- and it is a long term study- does include grad work, most through a doctorate. There is an argument for having more general studies in music and other areas of study that can eventually help with composing. For instance, poetry and art, or knowledge of history or social issues, can certainly deepen compositional vision. Science and electronics often intersect with music these days as well. Having the flexibility to take interesting gen eds and electives can be helpful (and a minor would hinder that).
There are many many schools where you can take music classes appropriate for composition development, as electives, and where you can have pieces performed. A student can compose on his or her own and attend summer programs and have the required three or four pieces for grad school.
Especially good for liberal arts colleges are the “little Ivies”, like Tufts, Amherst, Williams, Wesleyan, Bowdoin etc. Vassar and Sarah Lawrence come up a lot. Macalaster, Carleton, Kenyon, Grinnell. MIT MIT, Harvard and Brandeis in the Boston area, all have excellent music departments.
The one thing to keep in mind is that a school that DOES have a BM program on campus, meaning a school of music or conservatory, may offer fewer opportunities for a kid like yours than a school that doesn’t because the opportunities go to the BM music students. There are exceptions. But this fact may have skewed your search.
That said, look at Oberlin and Bard, both of which offer a BM in the conservatory but also have a BA in the college and some access for non music majors to music classes. As examples. Lawrence may as well.
Summary to this rambling post: look for general academic music programs at all kinds of colleges. If there is a school he likes in terms of size, location, “vibe”, finances AND engineering, just look at the music department site or email them and see if 1) compositions can be performed 2) if lessons are available on campus or nearby and 3) if theory and history classes can be taken by non-majors and 4) if there is a composition seminar open to non-majors (not essential honestly). Believe me , there are many many schools.
And doctoral students at top composition programs come from all kinds of schools and degree paths.
If engineering is his focus, make that a priority in the search, in other words, and assume that many of those choices will also work out for music, with adequate composition experience with or without a minor.
Again apologies for the lack of organization here. I was going to rewrite and condense but am posting as is and hope it is helpful.
Good luck!
ps Read the Double Degree Dilemma if you haven’t- it’s posted near the top of the forum
Wishing your son good luck in his path and know that it can work out in many different ways, and there is plenty of time.
Good luck!