Legally, that's probably correct. And yet, it points out the absurdity of allowing melodies to be copyrighted in the first place. There just aren't that many of them, especially when one limits to the musically plausible set.
"Non-trivial" doesn't have a formal definition, but it's guaranteed to be more complex than the 12^8 "melodies" generated here.
Actual plagiarism cases get much more complex, because lawyers will argue that specific features of the song, including the arrangement, combination of instruments, and so on, all contribute.
So the entire premise of this action is stupid. Nothing of value or interest has been copyrighted, and there is no chance the contents of that famous hard drive would stand up in a copyright claim against a commercial music release.
IMO this is basically a PR stunt.