I don't get it. It's US companies standing to loose their stronghold (near monopoly) on social, advertisement, and other forms of monetizing the web if the US creates a precedent for "national security" in this way, as in "we're welcoming social networks and free speech as long as it benefits the US and can be searched without warrant." Quite predictably, governments all over the world will be pressurized to question…
Isn't this just reciprocity? China banned a long list of media companies: FB, Google, YouTube, Twitter, Netflix, and every traditional media. Now the US is banning two apps made in China.
Further Trump didn't just say they had to be sold, but instead they have to be sold specifically to a US buyer. That is...incredible. He is effectively engaged in technology piracy. Then again he just announced new tariffs on Canadian aluminum -- leaving Russian and Chinese aluminum untouched, and just after the ratification of the revised NAFTA -- under the guise of "national security", so it's into serious parody territory now.
The US is currently a corrupt banana republic.
Regardless, China has an enormous number of US targets they can and likely will retaliate against. And when they do, be sure to thank Trump.