The county of Santa Clara already tried to screw Russ and Sally by simply banning gun shows on county fairgrounds. The county failed in that attempt, under a First Amendment commercial free speech argument, as I recall, and had to pay Russ & Sally's legal fees.
Whacked there, the anti-gun-show mole popped up again in two other counties - in Alameda their ordinance banned possession of firearms on county property, with the specific goal in mind of shutting down gun shows. Nevermind that county prison guards are not exempt, and violate the ordinance every time they check out a shotgun for prisoner transport - the county's goal was to shut down the gun show and drive Russ & Sally into bankruptcy, and that's what they've managed to do so far.
It's the fact that the county has banned possession of firearms which wound up bringing in the Second Amendment issue. In fact, it was a judge on the case who first put it into play - the case was originally intended to follow the winning First Amendment strategy from Santa Clara County.
I suspect that if the SCOTUS is inclined to take a Second Amendment case, this would be a good one - no criminals involved, and the only thing they'd have to overturn is a poorly-written county ordinance spoon-fed to the commissioners by the LCAV, rather than an enormous regulatory structure duly enacted by the California legislature as in the Silveira case.
We shall see.
If the second amendment were incorporated, they'd have a case. But as in US v. CRUIKSHANK, 92 U.S. 542 (1875), and others, the courts have ruled that:
"The second amendment declares that it shall not be infringed; but this, as has been seen, means no more than that it shall not be infringed by Congress. This is one of the amendments that has no other effect than to restrict the powers of the national government ..."
The local government is bound by the state constitution in matters of gun legislation. Since the California state constitution is mute on the RKBA, legislators are free to pass any gun law they feel they can get away with without being voted out of office.