I think your son has a definite chance to be accepted to all the publics you’ve mentioned, but as you know, none of them are guarantees, or even likelies (excluding Cali publics…that’s a whole different beast I don’t feel comfortable chancing on).
As @tamagotchi alluded to, I would spend significant time trying to find schools that are extremely likely to be affordable, extremely likely for acceptances, and that you son would be happy to attend.
Have you considered Indiana University? It’s music program is world renowned and it has lots of CS/info sci options that could be appealing. Your son would certainly get into the Honors College and would be likely to get merit aid as well, and it’s a great college town.
Another possibility would be Case Western. It wouldn’t necessarily be a safety, but if he shows interest, it’s better odds than some of the reachier ones. There’s music options, including the possibility of of classes at Cleveland Institute of Music right next door (besides the music classes at Case). And obviously, very strong STEM programs here.
If you son likes Michigan, I’d also take a look at U. of Wisconsin - Madison. It’s similarly strong academically, has great college life, etc, but is an easier admit than Michigan. I’d probably call this a likely rather than a safety, but wanted to throw it out as well.