Class-B ends at the shoreline on the pacific side of the peninsula (or at least it used to), not very far from the departure end of 28 L/R. I don't recall exactly, but I remember you could fly at about 700 ft as long as you remained west of the shoreline and be clear of Class B by a few hundred feet. It was very common to see planes following the shoreline, especially on weekends. On 120.5 I once heard a Virgin pilot complain about a traffic alert during takeoff to the tower controller, only to be told that the traffic was outside of Class B and there was nothing they could do about it.
It sounds like this plane did bust Bravo.