That's how it is currently and maybe also your opinion. But that doesn't mean it has to be like that in a society. It's your opinion that everything public can go private at any time (training proprietary private AI), but we can decide as a society that's not how we want to do things. We can require stuff that used public data to be public as well.

And yeah I kinda get to choose that. As democratic society, anything that the public (i.e. including me) decides, goes. Of course, if there are people like you that don't want stuff trained on public data to be required to be public, democracy will also work in the sense that we don't get that, as it is currently.