That's the point of the law. If a weapon fires with a round in the chamber that is not "indicated", the firearm will be "defective". SB 489 is not about making firearms " safer", it is about keeping manufacturers from selling in California due to increased liability.
At the same time, well made "pre SB 489" firearms will be kept off or slowly removed from the CA-DOJ, "Safe Gun List", thus completing the de facto disarming of Californians.