Well take this with a grain of salt since this is from my high school government class, but it would only apply when the treaty conflicts with state law. So I assume in this case the treaty apparently gives him the right to not provide easements which is in direct conflict with the California state law. Since the treaty is federal law, it supercedes over state law where there is a conflict. I believe this is based on the Constitution: https://en.wikipedia.org/wiki/Supremacy_Clause
That doesn't mean Khosla is exempted from building codes, unless that 1851 treaty says something like "The US government shall be able to regulations the manner in which buildings can be constructed on this land."
Again this is just from what I've gathered from other posters. I'm curious what clause they took from the 1851 treaty that made it clear that he doesn't need to provide easements. Maybe there was a clause that the property could never be seized for public good which the Mexican government put in to prevent the government from evicting Mexicans who wanted to stay on their land post sale.
That doesn't mean Khosla is exempted from building codes, unless that 1851 treaty says something like "The US government shall be able to regulations the manner in which buildings can be constructed on this land."
Again this is just from what I've gathered from other posters. I'm curious what clause they took from the 1851 treaty that made it clear that he doesn't need to provide easements. Maybe there was a clause that the property could never be seized for public good which the Mexican government put in to prevent the government from evicting Mexicans who wanted to stay on their land post sale.