They have perhaps attempted to lock the model, but so far I don't think we've seen any rulings that distillation or using the models to train other models is any less fair use than the original model training the companies have engaged in. Of course, the Authors Guild and other lawsuits against the model makers are arguing that it shouldn't be fair use. But if the AI companies prevail, there's no real argument to be made that training on their outputs isn't itself also fair use.

Further, I'm not sure how they've "captured the commons". By definition the "commons" belongs to us all. Nothing prevents someone else from doing the same thing. That is, unless the Authors Guild succeeds in splitting the courts over the fair use of AI training and the resolution of that split finds that training isn't fair use. Then the commons can only be used by companies or people with pockets deep enough to license the material in perpetuity.