Rayrick, this was the best post with specifics about what you/your son are looking for. As you have said, it will be very school-specific. You could contact music departments and ask. (I remember my daughter e-mailing Middlebury, which prompted an offer to find her a classical guitar teacher since there wasn’t one on staff!).
It sounds like a really good BA program would fit the bill if the extracurricular orchestra and ensembles meet your standards and a good teacher is available- which could be through the school or outside the school (city or conservatory nearby?).
With BA programs, also check how much of the coursework would be in music. For instance, at Harvard it is 50%, a quite high percentage of courses. And if there are any performance elements in theory or musicology classes, credit given for participation in ensembles or for lessons- all signs of support for instrumentalists I think.
Again strongly urge applications to both BM and BA programs (and double degree if he wants) if he is undecided. My daughter was undecided until April 30th of senior year 