Again NO one wants ZFS being in the mainline kernel, but being openly hostile against it, but accept closed Firmware (because they have to...who is the leech now?) is not completely honest.
You continue to conflate support for out of tree kernel modules as being similar to having a separate repository for firmware when they aren't the same thing at all. The Linux developers are not accepting firmware into the kernel at all, so there is no contradiction. The firmware is kept separate, just like OpenZFS is kept as a separate project from Linux. In both instances the user can choose to install an out of tree module such as OpenZFS as well as choose to install firmware on their system.
Furthermore it is not the Linux kernel developers that are packaging and shipping the firmware, it is the various Linux distributions who do that (or not in the case of FSF-approved distributions).