Less clear to me if that applies to forcible quarantine, but seems like it would definitely apply to public events.
On the point of large health risk, it doesn't seem unreasonable to me that every Warriors game is a perfect vector for community spread. I'm sure the health care professionals in the Bay Area would applaud this move.
> UNDER THE AUTHORITY OF CALIFORNIA HEALTH AND SAFETY CODE SECTIONS 101040, 101085, AND 120175, THE HEALTH OFFICER OF THE CITY AND COUNTY OF SAN FRANCISCO
Also it's hard to understate how devastating this virus can be if it spreads quickly. e.g. for people > 80 years old the mortality rate is 15%
https://www.businessinsider.com/coronavirus-death-age-older-...
These measures will absolutely prevent a significant number of people from dying. Does it matter if that population is not 'most' people?
Is this more of a "wink wink, nudge nudge" situation where corporations need government to "shut it all down" because the corporations don't want to lose face by appearing paranoid?