You can and should try to relax: The first wave of the calling campaign was, as stated, for URM students. Exceptionally high-achieving non-URM students like your son can expect to be called later.
FWIW, because my in-state, non-URM daughter interviewed last week for the Regents and Chancellors scholarship at Berkeley and earlier received Regents scholarship offers from other UC campuses, I think that it’s likely that she will be admitted to UCSD–but she was not contacted in what was clearly described as just “the first of the series” of UCSD calling campaigns.
biting my nails right now, especially because I’ve applied to the medical scholars program and don’t want to get screwed over without priority registration for classes