I've seen someone use a locking knife in front of a SAPD officer, who didn't blink an eye at it.
From what I understand from the wife of a SAPD officer, it is one of those laws that they enforce when they want to...which is rarely.
That seems to be the way it works. I see so many assisted-open knives in pockets that if they had any real kind of enforcement half of SA would be in jail.