What he is saying is that there is a bill that would provide for an ADU on a (e) triplex development, per SB 1069. Where as local zoning may not allow to turn a Triplex into a duplex, since you would be upping the DU/Acre, which is not allowed within Zoning Usually. Tyson is saying ADUs are by right on any multifamily parcel...but that is just taking the writer in Forbes word for it.
SB 1069 mentions allowing ADUs in Multifamily ZONES (which is different than a multifamly unit) if you refer to that section in the housing element 65589.4 it says Local Law Shall Allow which means they may limit as well, most jurisdictions do limit the ADU to ONLY a property with a permitted structure single family home.
San Francisco for example allows multiple ADUs within soft story renovations (ground floor parking)
Main point, check your local law - have an architect double check it. Having been interviewed multiple times about ADUs / building them and the state law, I know how those articles you reference are only partially accurate
In San Diego, I think you could build an ADU in certain circumstances if there is (2) Units on the property, so a duplex but I would double check that as well.
