He actually said that, and meant it.
Instead of putting SF city government in the business of supplying pot, they should post city police and state troopers at the existing private clinics to block any efforts by the feds to shut down the lawful trade in medical MJ, and threaten to sue the feds on 10th Amendment grounds if they interfere.
Of course, that would set a precedent for removing the feds from a host of other unconstitutional activities, namely the public dole which provides support for legions of DemocRAT voters. And we can't have that, can we?