hmmm...copyright of an *implementation* of an API is ok, but the API is just the declared interface to the software component. This has been ruled upon in the past, otherwise software like WINE (on Linux) would be in trouble. It *implements* the Windows API so Windows software can run on Linux but has no Windows code. Microsoft makes the API’s public information so people can right application software for it. Anybody can re-implement the API...and I’m a Software Architect that works with open source software and frequently have to deal with legal issues (GPLv2/3, Apache, etc.).
“hmmm...copyright of an *implementation* of an API is ok, but the API is just the declared interface to the software component.”
That sums it up.