Not correct, that post was about San Francisco only. The Bay Area is much, much larger, and has a density of ~1000 per sq mi. If the entire Bay Area were as dense as SF (not even close), that would be a megacity dwarfing NYC and Tokyo several times over.

They said sf which is strictly different than the bay area as it only has about 1/10th the total population and a significantly smaller fraction of the land. If you want to go from the silicon valley to sf its 45-50 miles.