Remember that he will be taking primarily General Ed classes at the CC, in order to be eligible for transfer.
For many students with a specific arts goal in mind, they can get discouraged without access to the college-level courses that were looking forward to.
My vote (just a stranger on the internet) would be to take the spot at SJSU, which is one of the more prestigious design programs in the state, and don’t look back. A UC, which by definition is more academically-oriented than hands-on, in the design field would not necessarily give him a better education.
If he should choose to go on to grad school, he’ll have an excellent portfolio from SJSU.