I think whether a UC or otherwise - he needs to meet transfer requirements. You won’t know until he tries. If he wants to live with dad - then he’ll try. Let’s say he doesn’t go to a UC But ends up at a CSU or other school like Arizona - so what ? The degree in engineering is what matters.
So either you take the sure bet or all bets are off.
I worry about the 69.75. Many HS kids struggle in college level work bcuz many HS grade inflate obnoxiously. Engineering is very hard and has a very high change major rate but your student, like others, will find out. When kids get a bad grade after being an A student, they tend to justify the why. It may be it just wasn’t his wheelbase at the college level or that he needs to relearn the subject. Happened to my brilliant engineer - had to WD and repeat a class and blamed the teacher. He later unblamed them. Just wasn’t ready and being new, didn’t feel comfortable going to office hrs. Lesson learned.
But to me you take the sure thing now or you reassess after a year in the community college.
UC or not UC is likely not a huge deal in engineering although may be in budget.
Good luck.