From article: „US security officials have expressed concern that the app, owned by Chinese firm ByteDance, could be used to collect the personal data of Americans.„
/s Fun days ahead. s/
The president can (effectively) order CFIUS (the Committee on Foreign Investment in the United States) to review ownership on national security grounds, and if they determine that it constitutes a security risk CFIUS can order that it be divested.
This happened with Grindr last year and the sale was closed in March.
Availability of an app for download is something quite different.
TikTok is also incorporated in the United States (TikTok Inc.) as a subsidiary of ByteDance. Their original acquisition of Musical.ly was reviewed by CFIUS last year, but I don't know the result (or if this is a continuation of the same review.)
... still, whatever happens with the US subsidiary should not, IIUC, affect whether or not the app can be downloaded.
Wow, sounds serious! I wonder if any other piece of software in the world has this problem. Perhaps Trump should ban all of those too. Better safe than sorry! :-(