Yep. The argument is that API specifications are not code, and reimplementing an API based on specifications is not a copyright infringement. It should not matter whether the specs are written in a natural language or a more formal one. Specs are more like ideas, and ideas cannot be copyrighted (the specification document itself could constitute a copyrighted work, though!)
The problem is that to reimplement the spec in this case, you do have to copy the formal declarations verbatim. Whether or not those "sentences" are protected, and pass the threshold of originality [1], is what is at stake here.
The problem is that to reimplement the spec in this case, you do have to copy the formal declarations verbatim. Whether or not those "sentences" are protected, and pass the threshold of originality [1], is what is at stake here.
[1] https://en.wikipedia.org/wiki/Threshold_of_originality