"This second point was particularly important in 1918, because that pandemic devastated prime-working-age adults."

That's not the case with COVID-19. Seems like a very important reason to me. COVID-19 has largely targeted retired folks. All the more reason to continue working and not quarantine.

Also, I know nothing about how comparable Los Angeles is to San Fran in 1918. Similar median age? They use Manufacturing jobs to quantify economic impact. Is that really comparable for both those cities? Or for all of the cases they compared? Maybe San Fran had lagged behind in manufacturing and was simply due to catch up? I don't know. Hard for me to take this as hard facts when I don't understand the underlying nuances to the real data.