Mostly, giving a source of trained models, and denying the possibility of making the new ones. I see unrestricted use of the big scale general-purpose models as a biggest threat, as they are effectivel "encyclopedias of everything", and can be used for very diverse and unpredictable things.

Who decides is also a very interesting question. Ideally, public consensus, but realisitcally, those who have the capabilities to enforce those limitations.