I only see one way to regulate models whose weights are public already.

Licenses hard-built into the GPU itself, through driver code or whatever. Nvidia and AMD can definitely do this. When you load the model into the GPU, they could check the exact weights, and if it's a 'banned' model they could shut it down.

Most of these models are too large for individuals to train from scratch, so you'd only need to ban the weights floating around. Fine tuning isn't possible either, since you need to load the original model first before you fine-tune it.

Yes, there would be ways to circumvent this, speaking as a lifelong pirate. But it's something that could be done by Nvidia, and would immediately massively increase the barrier to entry.