Earlier quoted context omitted.
They could. They would lose, though
A No-CD crack might not be transformative enough to warrant copyright protection as derivative work in the US. But they could sue in a jurisdiction that is more likely to give them a favorable outcome. Handling of derivative works and the minimum threshold for copyright varies considerably between countries.
A Harry Potter spin-off about Hermione (I don't know anything about HP, sorry in advanced) is a derivative of the original Harry Potter work. As I'm sure you are well aware, you cannot sell copies of your Hermione spin-off, because that'd be copyright infringement, because it is a derivative work.