If I regurgiate something I read in copyrighted book without proper license that also would be theft, no distinction there.

I'm not distributing my brain, at least same (but probably more restrictive) should apply to models - training is okay, but using and distributing should be limited by copyright

Explaining anything publicly based on my understanding I got reading books would be illegal following this logic. I'm not sure this is how it works.

They want to muddle the distinction between ideas and expression. You can't copyright ideas. Everyone is entitled to copy ideas.

It would not be illegal based on fair use (though you have to be careful there also), but if you try to regurgiate large portions of the book then it would be. And we do know that models regurgiate training material verbatim (Copilot)

Redistribution, and the scale of it.

Besides which, "learning" isn't a fair use exemption anyway.