Because UC’s weigh GPA MUCH higher than test scores, they’d be a poor fit for your son admissions-wise (very high odds of being turned down).
Also, the UC essay format is different from CommonApp (look it up on EssayHell).
He should focus on colleges that really like high scorers, like Vanderbilt or WashU.
What does he like about Berkeley CS?
Do you have 60K in a savings account for his college?