I’m not sure what one does with this information. To start with, there is a tradeoff of class size vs permanent (ladder) faculty.
At UC the approach is to have classes taught by ladder faculty which are necessarily limited in number; this means classes tend to be larger, especially lower-division which can have hundreds apiece. To ameliorate this UC has for decades scheduled a once/week “discussion” section (seldom in my experience a discussion) with a TA grad student. In popular majors at a UC even upper-division classes can have 75+ enrolled. For example at Davis the Schedule of Classes shows the upper-division ECE 150 “Operating Systems” has 194 enrolled and many other upper-division CS classes have 150+ students.
CSU by design provides smaller classes right from the time frosh start at college, often just 30 students. But they can’t work magic with the same resources; most classes are going to be taught by part-time faculty (lecturers) as you can see by looking at the CSULB faculty list at https://www.csulb.edu/college-of-engineering/cecs-faculty There is a surplus of PhDs in the US which means that in many subjects there are people with doctorates from very good universities trying to put together a living in academia, often while looking for a full-time slot. And I know people who had great lecturers at CSU who were retired and just taught a class a term for the enjoyment of teaching.
Since you mention your son is interested in cybersecurity it’s worth pointing out that CSULB has a minor in that available.
Since this is an advice forum, here’s my advice. The college experience at these schools differ so I’d lean towards the one that is the best fit. Any UC or CSU is more than capable of preparing undergrads for successful careers in CS. The difference in your son’s future is going to come down to how hard he works to master material that is at times difficult and often time consuming (any CS student will have stories of 2am struggles with a program due the next day that has a bug somewhere). Putting in effort to find internships is also important.