You seem to be mixing a few different things together here. There's a huge leap from something not being copyrightable to saying there is grounds for it to be m

You seem to be mixing a few different things together here. There's a huge leap from something not being copyrightable to saying there is grounds for it to be made public. No copyright would greatly limit the ability of model makers to legally restrict distribution if they made it to the public, but they'd be fully within their rights to keep them as trade secrets to the best of their ability. Trade secret law and practice is its own thing separate from copyright, lots of places have private data that isn't copyrightable (pure facts) but that's not the same as it being made public. Indeed part of the historic idea of certain areas of IP like patents was to encourage more stuff to be made public vs kept secret. >As it is their outputs are not copyrightable, it’s not a stretch to say models are public domain. With all respect this is kind of nonsensical. "Public domain" only applies to stuff that is copyrightable, if they simply aren't then it just never enters into the picture. And it not being patentable or copyrightable doesn't mean there is any requirement to share it. If it does get out though then that's mostly their own problem is all (though depending on jurisdiction and contract whoever did the leaking might get in trouble), and anyone else is free to figure it out on their own and share that and they can't do anything.