I think it would do the opposite. They would have a monopoly just handed to them, and a large market with no options. They'd have zero incentives to provide open weight models.

Right now, I think their incentive is the highest: Chinese AI companies are dropping competitive models left and right, and clearly American companies are feeling the pressure, given they're pulling every legal leg they can to suppress their competition. If we just remove the competition, Anthropic et al win. It's a temporary and short-sighted victory, but this is America. Every company is short-sighted, it's baked into our financial infrastructure.

US labs would have even less incentive to build open if we blocked foreign open weight models, and we'd be engaging in protectionism yet again, also giving them zero incentive to compete.