A copyright holder for the linux kernel, on the grounds that they are distributing an unlicensed derivative work thereof (there would be no need to show damages, there are statutory damages; it's definitely unlicensed, the part that's not clear is whether it's a derivative work). It's not really in the EFF's wheelhouse; mjg59 (who holds at least some kernel copyrights) claimed to be talking to the software freedom law center about his options. I'm unsure why he'd regard zfs.ko as more problematic than nvidia.ko (I mean fundamentally end users have the access they need to fix bugs in the ZFS source, the CDDL is basically the same as the GPL, whereas end users cannot fix bugs in the NVidia video drivers, not in some theoretical legal sense but in actual practice), and if the legal theory is correct then it surely applies equally well to both, but he's the one with standing to sue so it's his call. IANAL.