You're making an assumption that's debatable, but let's just assume it's correct. The reality is that China won't be the only to achieve such. In the same way that the US put arguably the best minds in the world towards developing the atom bomb, and within a few years the Soviets had theirs as well. Shortly thereafter they were popping up all over Europe. It's kind of the story of LLMs in general - once people saw it was genuinely possible, we went from one LLM company to them showing up everywhere.

It's highly improbable that any country retains a meaningfully persistent technological lead, and the soft power to be gained from providing models cheaply for society will probably greatly outweigh any sort of temporary strategic advantage that 'hoarding' could provide. And the reality is that nuclear weapons remain the kings of war, by an overwhelmingly wide margin. If the US and China or Russia got into a "real" war, that's pretty much the end of the world.