Do they think TikTok's user base will disappear overnight? There are a thousand competitors out there, and one of them will fill the gap. There may be a temporary disruption, sure, but that is still better than having a key chunk of the American economy (and young American eyeballs) directly controlled by the CCP.
There is a large amount of creators on the platform that live off their content and eCommerce enabled through the platform. So it disappearing overnight would severely impact people who have a majority of their livelihood through the app.
Facebook. Twitter. YouTube. They all have short form video, but TikTok has a lot of features that just don't exist on other platforms.