all the US would have to do to completely and entirely nuke an app (or an entire federated platform!) in the US would be to declare any foreign entity (country, state, corporation, person, etc) their "adversary".

Declaring a foreign country to be adversarial to the U.S. is a huge deal, and I highly doubt they would do so just to ban an app. They would much sooner try to pass an unrelated “special case” legislation, and the success of such a bill would hinge on the persuasiveness of the justification.

I’m fine with the U.S. forcing the sale of TikTok for a different reason, though: internet companies operating in China must be majority-owned and -operated by a Chinese domestic entity, yet the same restriction is not imposed on Chinese investments in U.S. internet companies. Asymmetric markets like this cede a great deal of influence to China, and it just doesn’t sit right with me.

It can often be beneficial to both parties when two countries influence each other, but such influence must be bilateral.