"And zfs.ko, as a self-contained file system module, is clearly not a derivative work of the Linux kernel but rather quite obviously a derivative work of OpenZFS and OpenSolaris. Equivalent exceptions have existed for many years, for various other stand alone, self-contained, non-GPL and even proprietary (hi, nvidia.ko) kernel modules."
This would be true if the resulting work were not a derivative work of the GPLed kernel. There's plenty of solid legal opinion that it is, and if you accept that then the GPL absolutely prevents distributing it in the form of a binary module.
Sorry, I downvoted you by accident, while focusing my browser window.