Your whole argument seems to rest on the idea that the AI race is entirely contained within the United States, where we can regulate them.

And that no other country might just take the open weights and continue right on with the advancements in private?

No, it rests on the idea that almost all of the money, most of the people, and the GPUs are here.

Any country would be able to take the open weights and keep going in private. But countries like China can already do that today, since the weights are almost certainly already in foreign hands due to espionage.

What they can't do is fund the next frontier run at today's pace without selling into the US market, and selling into the US market can require opening the weights.