By California law, there is no such thing as ownership of a beach. All beach sands are public, by statute. You are asking who the owner is, but there is no owner of the rights of access or exclusivity, by law.

Of course, Khosla should have access to the lands he owns. Under California law, land is something that private citizens can own. A beach is not one of those things.

EDIT: that being said, private property rights do not always or even typically grant you exclusivity. Many jurisdictions have various requirements on what private landowners must allow the public to do on their land. For example, many jurisdictions have freedom to roam provisions, which ensure that the public has access to wilderness, even if privately owned. The United States does not have this in general, but it is certainly within the purview of the states to legislate such things. In many US cities, homeowners own the sidewalk and must maintain it, but allow the public access. This is written in the deed, or mandated by statue.