Rank of schools where he was not admitted to CS is meaningless 
He will receive a good education at UMN, and it is respected by employers and graduate schools. My son hears good things from friends who are students there, too.
He should go ahead and apply for housing (if he hasnāt already), since the housing application date determines priority. https://housing.umn.edu/live/apply
Can you afford UMN? If so, thatās the best choice.
Informatics at UIUC is very good - not as technical but he should be able to add a minor ā he can email the Dept and ask what minors they would recommend - if itās easy or competitive to add DS or ā¦ as a minor.
Seconding applying to Housing regardless, in order to secure a place.
To make the huge university smaller, he can apply to special livƬng learning communities. If he got into Honors he should absolutely select that for Housing. Otherwise, here are some that may be of interest
https://housing.umn.edu/llcs/at-home
https://housing.umn.edu/llcs/taylor
https://housing.umn.edu/llcs/stem-diversity
Yea! Still affordable! The UMN give $3k president scholarship, so only $33k with 20k living, $53k and total $210k? In UIUC ,20k+20k ,total $160k, not cheap either!
If you can afford it, then itās a no brainer.
Students at UMNās COE have ACT scores in the 32-34 range with 25% hitting 35 or 36ā¦ and 25% also had a GPA 3.9-4.0! Itās a highly competitive college to get into. In addition, being located in a metropolis with hundreds of companies makes externships&internships easy to arrange for a solid resume.
Your son will not be bored 
and will have many, many peers.
Thanks for your suggestions! You confirmed me for UMN!
Without direct admission to the CS major, the likelihood of getting into the CS major after enrolling there is very low.
Is Applied math or stat good in UW?
If the student want to study applied math or statistics, and is admitted to the major in competitive holistic secondary admission.
It doesnāt matter because obstacles make that really difficult to get if he was only admitted as āpre scienceā.
He can always apply there for a Masterās degree (a degree from UMN with a solid GPA and a good resume with research or internships, examples of leadership, etc., will be highly respected).