No, they’re threatened by two things:
1. Equipping the CCP with a sensor placed in the pockets of millions of American citizens. This is already a problem when American companies are doing it for ad targeting purposes. But to do the same and funnel the data to an increasingly militaristic near-peer adversary? It in fact makes it qualitatively, not just quantitatively, different.
2. Tiktok opaquely selects which content it shows users. Again, American social media companies do this to a lesser degree (non-chronological feeds), but they don’t tweak their algorithms at the direction of the government to opaquely modify the information environment a citizen exists in. Note that there is currently very public tension between the US establishment and these companies because yes, authoritarians love this capability and no, they don’t yet have it in the US. Tiktok has no ability to refuse CCP’s requests to, e.g. erase any references to their concentration camps or to amplify claims that Bill Gates is trying to inject microchips via the COVID vaccine.
Whether a US executive should be able to single handedly make such a decree, I really don’t know. It doesn’t seem right to me but I ought to think about it more. What is 100% obvious to anyone looking at TikTok and the CCP with clear eyes is that it is a huge threat.