Please let me know if you as a private citizen without law degree find any of the things in SPL-1.0 scary. We can then compare our notes.
Sure, I find a lot of things scary with the SPL. If you're saying that it is an awful licence I'm not arguing with that. I wouldn't feel at home using SPL'd software.
I understand the current OpenZFS code is under the CDDL and according to wikipedia (1) "This license [SPL] has been superseded by the Common Development and Distribution License, which is also derived from the MPL" (this depends on how much trust you put on Wikipedia as a reliable source).
OpenZFS uses a different code from solaris. They imported the last open source (CDDL licensed) code and then started to work on it. Solaris made subsequent versions of their codebase closed sourced. As a result, the latest versions of solari's ZFS are different from OpenZFS. OpenZFS is CDDL'd and Sun ZFS (since v38) is closed-sourced.
I only have a cursory understanding on how licenses work, but as far as I know, they cannot change or revert the licence on a piece of code they released. What I'm arguing is precisely this. The code *is* unlikely to switch to the SPL (or any other license), partly because it is an old license (and superseeded) and partly because it is not possible anyway.
Oracle can still sue, nothing is stopping them from doing so, but I think they are unlikely to succeed. The foundation probably does too, I have no reason to believe they didn't do their homework, given that they also have lawyers, and the companies that build their products on top of ZFS/FreeBSD also have lawyers. In any case I don't think Oracle cares anymore. They have their own version of ZFS, which they are not sharing. But just in case they sue, the Foundation has lawyers, and the companies that built their products on top of FreeBSD also have lawyers, so they can just counter sue. Sun would be loosing a lot of money for something they probably don't care that much about.
[1] -
https://en.wikipedia.org/wiki/Sun_Public_License
