A US citizen distributing foreign media themselves is quite different than what is effectively a directly controlled broadcast owned by a foreign government.
The comment I originally replied to likened tiktok to a printing press, but that's not quite right.
Imagine a printing press owned by an enemy that would subtly manipulate the text of whatever you tried to print. Or maybe it would omit entire articles from certain recipients of the newspaper, or reorganize the page layout to emphasize different things than the editor intended.
We wouldn't allow this hypothetical printing press controlled by a hostile foreign government to be sold in the US, we would be crazy to.
The US is widely against even having its own government own communication platforms.
So if you want to make the same argument, you will have to declare china's CCP to be a terrorist organization - and all of the legal implications that entails.
When one country tries to cause chaos in another, they use a two pronged approach. (1) they offer a country's aristocracy the ability to enrich themselves at the cost of their people. This could be things like cheap labor, gas pipelines, or being the guarantor of loans. (2) They tell a countries peasantry that the worlds problems are simple and that their government is their enemy and failing them. This is only empowered by having compromised their aristocracy, so their government is failing them.
Then they put their fingers on the scale by providing resources (weapons, funding, press, intelligence, etc.) to an aligned entity capable of promoting their interests.
It's worth considering that the great firewall of china exists explicitly because the Chinese government (rationally) thinks it's risky to subject people who were subsistence farming a generation ago to foreign influence.
The cost of freedom is responsibility, and if you have an irresponsible (read: poorly educated/non critical thinking) populace, then people will unwittingly surrender their freedom. Freedom means the freedom to do the wrong thing, but that can result in bending or breaking.