You can't treat models like drugs. One is physical and the other is digital.
To your point, the war on drugs is a colossal failure which has achieved none of the objectives it set out to do. You can now order drugs from your mobile phone in any major city in the west and the purity is often higher and they deliver it to your door sometimes faster than Uber eats.
See also for example digital piracy where the entertainment industry has lobbied, cajoled and convinced many governments around the world to criminalize the distribution of their content over the internet for free.
What was the result? After 20 years of DMCA takedowns, countless celebrations that torrents were dead, and many other self congratulations in the media, you can now find 10 different pirate streaming websites where all the episodes of pretty much any show that was ever created are available for free in 5 five minutes flat and the image quality is as good as on your Netflix or Paramount account.
The only way such a ban of open weights model would work is if you were to replicate the great firewall of China in the US and in Europe and even that doesn't work completely.
As for sanctions, China and India are buying Russian oil in enormous quantities as we speak and they don't really care that Europe and the US have put sanctions on Russia and I suspect you will see the same results with models coming from China.
If a country has a choice to either use the expensive SOTA models approved by Washington or Europe only or using the cheaper and not so SOTA models, why would they use the US ones? Why would it be in there interest?