So when the copyright holder considers the work done and stops changing it at all, it's now FOSS too?
I'll repeat myself, as you ignored the important part:
> The copyright holder could decide to modify the learning set before pressing the "start" button, you can't.
Even if the copyright holder does not intent to retrain their model, you are not in the same position as them. The choices they made at initial training are now ingrained in the model, putting them at an advantage over anyone else if you can't inspect and change those choices. They got to decide, you did not. Your only option to be in a similar position is to start from scratch.