CCS Computing at in-state rates is a great opportunity, but it seems that he wants engineering. There is CE in the engineering school; would he be able to supplement with CE coursework? The full ABET degree might not matter if he’s CS-focused but wants some hardware background as well.
He must have gotten a nice merit award at Purdue, if the cost is comparable to UCSB; and Honors makes it even more attractive.
I would eliminate UIUC. Why pay almost double, pass up the nice honors programs, and have to switch majors? It’s a good school but I don’t see what about it would justify those tradeoffs.