My impression is that some of the Linux kernel devs are anti-anything that's not GPL-compatible, of any sort, regardless of the particulars.
Linus himself also made remarks about ZFS at one point that were pretty...hostile. [1] [2]
> The fact is, the whole point of the GPL is that you're being "paid" in terms of tit-for-tat: we give source code to you for free, but we want source code improvements back. If you don't do that but instead say "I think this is _legal_, but I'm not going to help you" you certainly don't get any help from us.
> So things that are outside the kernel tree simply do not matter to us. They get absolutely zero attention. We simply don't care. It's that simple.
> And things that don't do that "give back" have no business talking about us being assholes when we don't care about them.
> See?
Note that there's at least one unfixed Linux kernel bug that was found by OpenZFS users, reproducible without using OpenZFS in any way, reported with a patch, and ignored. [3]
Linus himself also made remarks about ZFS at one point that were pretty...hostile. [1] [2]
> The fact is, the whole point of the GPL is that you're being "paid" in terms of tit-for-tat: we give source code to you for free, but we want source code improvements back. If you don't do that but instead say "I think this is _legal_, but I'm not going to help you" you certainly don't get any help from us.
> So things that are outside the kernel tree simply do not matter to us. They get absolutely zero attention. We simply don't care. It's that simple.
> And things that don't do that "give back" have no business talking about us being assholes when we don't care about them.
> See?
Note that there's at least one unfixed Linux kernel bug that was found by OpenZFS users, reproducible without using OpenZFS in any way, reported with a patch, and ignored. [3]
So "not giving back" is a dubious claim.
[1] - https://arstechnica.com/gadgets/2020/01/linus-torvalds-zfs-s...
[2] - https://www.realworldtech.com/forum/?threadid=189711&curpost...
[3] - https://bugzilla.kernel.org/show_bug.cgi?id=212295