While technically correct, they do have it in China itself, it’s a modified version called Douyin. It is more restricted, censored and tightly controlled.

I agree that it is a cyberweapon, but don’t think that it’s only used against foreigners, they use it just as much to observe and influence their own population.

Finally, I would like to point out that to a lesser extent this is also the case for a lot of USA owned social media and tech companies. Edward Snowden’s revelations for example indicate this. While the extent of government control and influence is much larger in China, I wouldn’t underestimate the influences of Meta, Google and Microsoft for example.