Maybe some kind of corn snake? He's in southern California, and the bike path was along the San Diego river.
You're correct. Nope, don't mess with nonvenomous snakes, for their sake.*
And really don't mess with venomous snakes, for your sake.
*Except if you're in the Everglades and you're absolutely sure it's an invasive Burmese python and not one of the native species the pythons have been eating to extinction. Then you should kill it quickly. But don't eat it, they contain a lot of mercury.