(Trying to just be sad about his loss and not angry at what San Francisco has become, but it's hard.)
From tweets it appears that he had moved to Miami, came back to SF on a work trip for a day - and this happened.
Many cities with high homicide rates have them specifically because of gang activities and they don’t have any relevance to regular citizens.
Additionally, gun friendly states with “stand your ground” laws will have higher homicide rates just from self defense in robberies.
Tldr; homicide rate is meaningless to how safe you are as a bystander.
There was a notable SF->Miami exodus during COVID, we don't need to attribute reasoning we don't know here.
https://www.sfgate.com/bayarea/article/mill-valley-man-kille...
Additionally, if you search through Jake Shield's Twitter feed, you'll find instances where Bob Lee talked to him. [3][4]
UPDATE: Jake Shields confirms it was Bob Lee. [5]
[1] https://twitter.com/jakeshieldsajj/status/164344881917319577...
[2] https://twitter.com/jakeshieldsajj/status/164346184739026124...
[3] https://twitter.com/crazybob/status/1538245201734406144?s=20
[4] https://twitter.com/crazybob/status/1587914051715227652?s=20
[5] https://twitter.com/jakeshieldsajj/status/164347000156601548...