There's actually interesting issues with how property paid for through mortgages are impacted by nuclear regulations. I recall something deep in my mortgage about how (I think) the nuclear regulatory control act placed restrictions on local use vis a vis nuclear energy.
In general the court seems to try to go to the easiest decision point in a case. The copyrightability of an API is less relevant if the user being sued should win regardless because of fair use. This is better than a plurality decision where there's multiple reasonings on API copywrite that make future decisions difficult. Here at least the court gives guidance on how to think about evaluating fair use in this context, which lower courts can apply.