What does it take to create a derivative work?

DesignsfromMahrs takes old comic books and sews the pages together to create bags. In the 9th Circuit, this is probably enough to constitute a derivative work (at least if you get a panel that is committed to following prior panels), but what about elsewhere? It doesn't seem like the creativity in putting four or five pages together in a new configuration should suffice for copyrightability, but I could be wrong about that. In theory, the justification for a heightened creativity standard for derivative works is to avoid blocking other creators of derivative works when (if) the underlying work enters the public domain, and you could avoid that problem by saying that only exact duplication of a bag would infringe the derivative bag.

(If I recognized the comics, I would probably buy one of these bags. But there is probably a reason they're not using big-name DC/Marvel comics in the first place, either to appeal to people whose comics tastes are more refined than mine or to avoid DC/Marvel lawyers.)