I haven't read too closely, but no one is building meaningfully affordable housing in Atherton. Each unit in the development would easily sell for millions.
CA/the bay area should focus on packing high density housing closer to transit lines, not lifting apartments in areas that are an hour+ walk from transit to score political points.
To the best of my knowledge it's mandated by the state — our old city council used to refer to our town as "complete" and slow rolled housing an approach which, to the best of my knowledge, would just yield state intervention with local decision-makers removed.