[rguetzkow]

I am not a lawyer and the opinions expressed herein are my own.

The argument is not that the API itself is protected by copyright. This wouldn't work anyway, as APIs aren't protected by copyright under EU law. From my understanding the argument is that the implementation of the API is protected by copyright. If the script/add-on for Blender depends on the `bpy` package (Blender's implementation of the API) and is not being able to function without out it, then it should be considered a "single program" based on the interpretation of the FSF provided in their FAQ [0]. Thus the script/add-on is derivative work and subject to the GPL license. This assumes that the interpretation the FSFs provides in their FAQ would hold up in court.

[0] https://www.gnu.org/licenses/gpl-faq.en.html#GPLPlugins