They vast majority of poor in SF grew up there or in nearby areas, they didn't migrate there like the economic elite have.
Page 33, under the subtitle "Place of Residence"
It's true, it doesn't measure length of stay, but they came from SF and claiming it's still an external problem with no evidence seems particularly disingenuous.
Given historical population growth of California, I think it's not a winning argument. Very few of California's residents have moral ground to live here at the exclusion of others. Pretty much everyone moved here. The only way forward is to allow enough homes to be built for everyone who wants to live here.