Earlier quoted context omitted.
You might be surprised to learn that the work of a copywriter is also copyrighted.
That's a weird thing to say in response to someone saying "the text was rewritten, so it's not actually a copy"
The law cares about the process you took to get something, not just the final output. Stealing something and then changing some stuff to try to make it not look identical doesn't invalidate the fact that you stole it. I can't download someone's song, strip out the bass line and record my own, and then pass off the new song combining the old music with my bass recording as an original song.
I don't know whether that's what happened here or claim to know exactly what the constraints of IP law for this specific instance are, but "some stuff was changed" does not necessarily seem sufficient as a defense in general. Depending on the exact type of IP law that covers this there are questions like whether the changes were substantial enough to make it an original work or whether the way that the old stuff was used constitutes fair use.