Not sure about the California bill, but the similar shit out of Washington state does have language for subtractive manufacturing as well as additive. They basically are targeting any computer controlled manufacturing.

It all feels so obviously stupid when there are people on the internet selling partially complete metal parts with instructions for how to finish them completely unrestricted. They obviously aren't worried about stopping the "ghost gun problem", they are worried about people having the means of production and the right to repair things they own.