That's not what free software is about
Free Software, no matter what license, also means that your APIs are simple enough so they can be re-implemented easily. It's the kind of competition which used to make the unixoid world so good. And yes, Free Software has been reimplemented by commercial vendors multiple times. It's a good thing.
What the author is doing here is just repeating what Oracle claims. Oracle is, as we all know, not really a proponent of Free Software.