That's entirely possible, but it's also not super-great if this precedent stands. APIs have generally been understood to be a tool for communicating between lay

That's entirely possible, but it's also not super-great if this precedent stands. APIs have generally been understood to be a tool for communicating between layers, not a work of art that are themselves copyrightable and proprietary. It throws sand in the gears of cross-system integration if a company can get you on their copyright ownership of an API (especially since in the US, copyright is assumed and one is not required to file formally for it).