If it was actually about privacy or whatever, they would simply ban the privacy-violating practices, not the app itself.
Except once again, PRC doesn't ban US services, they force them to comply with PRC laws that has onerous moderation overheads. And these services refused back when SV was riding high on free speech, aka low cost moderation.
IMO US wants to ban Tik Tok because they can't implement broad content/privacy rules like in PRC. Whether due to tech lobbying, because it's politically difficult, or it's politically inconvenient - US platforms implementing elevated standards will ripple expectations and costs across global markets where they operate.
Also keep in mind that even PRC hasn't tried to force of sale US companies due to national security. Require joint ventures / ramp up costs, sure. With Oracle deal out, TikTok can't even operate in US the same way iCloud can operate in PRC.
Though it's not as official as in China, major American social networks are increasingly heavily moderated, and increasingly do work closely with govt and close-to-government entities to enact desired moderation (censorship, if you prefer) policies.
They do this "voluntarily", but it's not clear they could actually decline w/o suffering consequences.
This is perhaps somewhat less true at Twitter post-Elon aquisition. It will be interesting to see how it plays out.
Let's say TikTok becomes a fully-fledged US company.
Is that actually something under the US government's control? I mean...will the US government actually do anything substantive to reign in the privacy violations of an American company?
Yeah, right...
In other words, it's less a user privacy issue and more a national security issue.
Because that isn't remotely the case. A backdoor exists for everyone, or it doesn't exist.