The question is…can your family afford to pay and are willing to pay the additional $20,000 a year. If so, then your son should be able to freely choose.
If the additional $20,000 is out of budget, then your son needs to know that now…in the event that CWRU does not increase their aid offer. I think expecting a $20,000 increase is expecting a lot…but you won’t know until they respond to your request.