Extend your example a bit and the issue gets murky though. Consider /The Wind Done Gone/ which was a retelling of the Gone With the Wind story from the eyes of a slave. It had no text from the original work in it, and even avoided using the character names, but it had the same plot and was unquestionably "inspired" by Mitchell's book.
The estate of Mrs. Mitchell got an injunction from the courts against its sell, eventually leading to a settlement.
So the point is that a work need not directly incorporate another work to be considered derivative and infringing. And there is a small contingent of Linux developers who are rattling the cage to go after NVidia with the argument that the NVidia drivers are inspired by and therefore infringing on Linux, although it doesn't look like anything is going to come of it.
What this all means with regards to GCC and the FSF.. I can't say, except that these issues are a lot more complicated than people tend to admit, and that these legal discussions on websites like this are pretty close to the three blind mice trying to come to terms with the elephant. We don't have the expertise -- and we've not done the research -- to have informed opinions on this matter. And that's as true of Corbet as it is of us posters.