This hypothesis has already been tested by Stanford and found to be false.
https://www.sfchronicle.com/bayarea/article/Exclusive-Autops...
https://www.cnn.com/2020/04/23/us/california-woman-first-cor...
tl;dr
first covid death (feb 6) is nearly a month earlier than previously official first US covid death (feb 26), and also from community spread. suggesting it was in the bay area at least half a month earlier than that.
So how do we move this from a collection of anecdotes and immediate dismissal to prioritizing some antibody tests to the bay area. Possibly reopening it faster and keeping it open.
Just acknowledging the possibility can influence public policy, and the research that some other people want to see before they can acknowledge it.