again, "not granting cert" ≠ "upholds"
Again, if the Supreme had granted cert here, why would they overturn this?
For the reasons advanced by the petitioners in their petition for cert? There's an interesting question here about whether a particular statute was intended to displace common-law sovereign immunity for agents of foreign governments; they point to a split in authority between the Ninth Circuit decision below and [their interpretation of] decisions in the 4th and DC Circuits. Not unusual for the Court to take such a case to resolve a circuit split about how to interpret a federal statute.
And you're missing the point. When the Court decides a case, it becomes binding law nationwide. When they deny a petition for cert, the lower court precedent remains law only in the relevant circuit (here, the Ninth). "Upholds" suggests they have affirmatively embraced Meta's argument here rather than declining to determine whether it is correct or not.