In what way does TikTok operating challenge U.S. sovereignty? This is 2003 all over again.
In fact, I think the biggest threat to the US is the suspension of the first amendment because of the age old boogeyman of national security. Propaganda has always existed. The way to respond to bad speech is more speech. Banning it makes it forbidden and thus captivating, don't you know about the Streisand Effect?
If the transmission of media is a threat to national sovereignty, if the fate of the country can be undermined with memes, then we have already lost. The US should disconnect itself from the global internet.
In what conflict was giving an adversary a full attack surface for propanda etc. deemed the right approach?
The US had more a massive propaganda effort of their own during WWII, but yes we literally rounded up every person of Japanese descent and put them in camps, which should never happen again. Yes, there was a lot of really terrible censorship later in the Cold War like McCarthyism, which is the danger I am worried about. The public became so xenophobic that you could kill an actor's career in Hollywood by telling an agent that they had a copy of The Communist Manifesto. Simply having copies of books written by authors from the wrong country automatically made you "unamerican" and a traitor.
This is the path I fear we are going down again. The government is saying it knows best about what media we cannot be trusted to consume.
Using a freedom of information argument for Americans is a stronger position, but that isn't guaranteed by the Bill of Rights.
This is going further than I want to go from a civil rights perspective, but there is at least some precedent. Corporate sanctions and bans have been used very effectively, as Huawei experienced not so long ago.
edit: Decedent western rock and roll also challenged the ideological purity of the Soviet Union so record imports were banned for a very long time.