I think his GPA is holding him back. UCs are very GPA driven. I know few 4.0 UWGPA and 1600-1700 SAT applicants who got into UCLA.
My son is not similar to yours in terms of stats or field of interest, but he went the CC route and was accepted last Fall for the UCD TAG program. I believe he applied as a psychology major. If your son is really set on UCD, that might be something to look into. My son has not received final admittance from UCD yet, but he has been formally accepted by UCSB so far.
I went through all this back in 2007 with my daughter, who went to UCB straight from high school. Totally different ball game with my son, 9 years later, and he has not wanted much involvement on my part, so I don’t know all his stats etc. CC route sure is cheaper too!
Good luck to you and your son whatever you decide.