That's because:
* Saying it'll get banned makes for a more sensational headline.
* Saying it'll get banned is accurate enough for most practical purposes.
* Saying it'll get banned is simpler than explaining the details of divestiture. Most Americans probably don't even know what "divest" means without pulling out a dictionary.
Speaking with some younger American co-workers in the past, their suspicion/hatred of their own country is astounding to see and it seems to have coincidentally begun after TikTok entered US market a few months before US elections.
So the worry seems to be that young American voters exposed to a foreign social platform will influence upcoming elections. I do not think this is far fetched as multiple countries have come out to expose various tactics by certain countries to influence perception.
Speaking as an American, our country was founded on the principles of being apprehensive of governments including our own. Being suspicious of our own government is a very American thing and should not be understood as surprising.
See our Declaration of Independence for further reading and context.