Missing the Forest for the Trees
I am an old curmudgeon, I don't understand TikTok. That said, the idea that TikTok poses some massive threat seems silly when the US is very happy to allow any other social media platform (And most tech companies) to essentially act as private surveillance companies selling personal data for profit. Practically the entire internet economy is built on the buying, selling and use of this information. Singling out TikTok is just sinophobia, I seriously doubt that the information they can get from TikTok is materially more important than all the information on the open market right now. The US needs comprehensive privacy protections, but I imagine that would be bad for profits and won't be happening.
The idea that China could use the platform to influence people may have more reality to it, but again it ignores the insane ideas that have sprouted up on US owned social media platforms (Which foreign actors could influence anyway). Facebook didn't need to be owned by a hostile nation to spread conspiracy theories like Q-Anon, and that isn't even considering the damage they have done overseas. Social media sites all make content decisions that influence public perceptions.
I can't tell if this is just cold war style fearmongering or if these politicians just prefer the US companies not face competition in the market, but it seems pretty unlikely to me that this is all in good faith.