Yale does not have a BM, and a few years ago started the BA/MM program. Most undergrads, I have been told, would study with a grad student in the SOM. So in that case, the presence of SOM grad students is both a pro and a con, since the best teachers would go to the grad students (and double degree students).
I think you are underestimating the value of a worthwhile music supplement in terms of a boost to admission chances. Of course “worthwhile” is key and it may also be somewhat instrument-dependent. Does he do conservatory prep or any summer programs? The music resume included in the supplement can help too. In our experience, Ivies just wanted a 3 minute cued excerpt of one piece- not like a conservatory at all.
It is important to check on orchestral opportunities, particularly in smaller schools.
Has he or have you read the “Double Degree Dilemma” essay in the music major forum? It is fine to apply to both performance schools and non-performance schools , but personally I don’t think the latter should be chosen simply because he did not get in to a top tier music school. Does he want 3/4 classes in music or 1/4 classes in music?
At some point, and yes it can be late in senior year, he will have to decide between a BM and BA (BA in music or something else). Things can change in a year. If he truly wants performance I do not understand substituting BA programs for “lower level” music programs. There are many options for BM’s that aren’t top tier but can lead to top tier grad school and careers.
To be clear I am a fan of BA’s for music students with continued (often funded) lessons and performance (both for credit, often). I personally know and/or have talked with career musicians who took that route, sometimes majoring in something else. (They are not orchestral musicians generally.) But if a student wants immersion in music, a BM is the preferred path and I would think a student who is committed to music would consider more schools for that degree.
I’ll send you a PM.