The reporting on this topic (especially headlines) has been generally quite poor. You really have to dig in to understand what is going on. See this cousin comment for details on how he has won on most of the merits:
That's only true if you're talking about different arguments for the same issue. Here, there are multiple issues: (1) does Khosla need a permit; and (2) does the public have an easement across his land?
It's worth reading Surfrider Foundation's opposition to Khosla's Supreme Court certiorari petition: https://www.supremecourt.gov/DocketPDF/17/17-1198/50086/2018.... Their #1 argument was that the Supreme Court shouldn't take this case now because Khosla hasn't even applied for a permit. (He was just fighting an injunction that keeps him from closing the road until he gets a permit.)
But eventually, the State will have to deny Khosla the permit, and justify doing so. It will be very hard for the State to say "we are going to keep you from building a fence to close this road," while simultaneously acknowledging "the public doesn't actually have a right to use this road." If the State uses its permitting power to effectively give itself an easement that doesn't otherwise exist, that will tee up the takings argument that was only theoretical in the Supreme Court petition. And I like Khosla's odds on prevailing on that argument.
Courts have so far ruled that, for various reasons, the 1976 California Coastal Act doesn't apply at all to this piece of land. They have also ruled that the previous use of the land didn't create any sort of government easement over the property.
https://news.ycombinator.com/item?id=21974524