Honestly I think they could relatively effectively curb non-state-level use in a lot of situations. If the risk of using them or disseminating them were controlled even nearly as tightly as copyright law, that relatively low bar would already filter out most users. Understand that it's technically non-trivial to set up and use these models. You might see them continue as warez and the like through torrent sites, but they aren't as simple as a pirated movie–you can't just copy it over and play it in most cases. 100% reduction is impossible by any reasonable means, but even 90% reduction would go a long way toward avoiding just one-off acts