Colleges don’t want well-rounded applicants. They want a well-rounded class.
It means 1) academically well-rounded student = took all 5 cores all 5 years, has made academic choices that indicate where academic interest lie (ie, in Jr/Sr years, correspond to major as indicated on application)+2) EC-pointy so they can fill a role on campus. The combination of admitted students should thus be 1) academically: all, likely to graduate and succeed 2) each, needed to make campus life thriving and possibly news worthy and thus brining something unique, in depth, at a high level, and different from what others bring.
If he’s a good chorus singer, look into St Olaf (+ Luther, Concordia Moorhead…) which have excellent choirs and always need good male singers. They even offer music scholarships.