Meanwhile, this works, is under active development, and is essentially at HEAD of both openzfs and zfsonlinux:
At that point the word came down from Apple Legal to Engineering that it wasn't happening. And there's nothing more insurmountable than your own legal department.
Just to note: It doesn't really work this way, even at Apple.
It really means "legal was better at arguing their side than whoever argued against them to the SVP/CEO who made the decision"
While apple is worse than most (from talking to friends and counterparts), no company, even Apple, is so silly that the legal department can't be overruled (any general purpose software company that works like that goes bankrupt pretty quickly).
It just takes a really good business case for doing so, and none existed here.
That is,if it had been considered super-mission-critical, it just would have happened anyway, they would have taken the risk.
(I kind of just hate when these stories get portrayed as legal ruling with an iron fist with nobody having any say over them.)