The reason TikTok is such a threat is because it's not a Chinese platform, it's a global platform controlled by China. Theoretically at any point China could use it to drag foreign users into their sphere of influence. Twitter was a threat for the exact same reason. The difference being it's not a theoretical future problem. Its owner is already actively spreading Russian propaganda, amplifying fascists talking points, and openly admitted to manipulating the algorithm for his own personal gain. You currently have hundreds of millions of international users under the influence of a far-right pro-Russia Autocrat. If I was in charge of banning social media platforms I'd be watching TikTok very very closely, but I'd be holding a Defcon1 five alarm fire meeting about Twitter right now.