I'm curious why you think Apple would support any effort that does not benefit their bottom line?

Users buying Macs to put BSD on them are less likely to buy things in the Mac App Store.

Apple's attitude towards other OSes running on their hardware is less "supportive" and more "barely tolerates". Also as a general rule Apple doesn't contribute much to open source outside of some high profile projects like Swift and Webkit.

Apple is struggling to make MacOS functional, why would they contribute engineering time to another OS?

I still remember when MacOS being based on BSD had the community excited about the future

Apple publishes the sources to the GPL BSD code they have to but that’s where the support ends.

Apple has no interest in assisting a competing operating system.

I would expect if anyone even considered it, they’d immediately reject the idea, as they clearly believe that Apple retains ownership of the computers they “sell” and should control the software you could run on them.

Apple hasn't done any work that would be useful.