As far as we know, Tiktok is operated on US servers by Oracle. While it might have been possible to find another cloud provider and move all US data there, I can see them not wanting to do that given that there was no point if the app isn't distributed in the US anymore.
It was a gambit used for net neutrality in 2014 https://en.wikipedia.org/wiki/Internet_Slowdown_Day
Nico argued TikTok made the minimum change required by law.
They were telling users who to blame and who to thank because in this specific case, the blame and the thank are pretty clear. The Biden administration approved the ban, and the Trump administration reversed it. Blaming one and thanking the other is also hardly surprising.
There is no question that TikTok is a politically sensitive app and the US/China are very nearly in the funnel to a major war so a lot of the usual niceties are questionable. Previously the US has attempted something that looked a lot like a black-bag kidnapping of a Chinese industrialist [0]. I'd imagine that the TikTok people are acutely sensitive towards how the law is actually going to be interpreted and enforced in practice.
[1] https://en.wikipedia.org/wiki/Protests_against_SOPA_and_PIPA...
Jan 17: Biden administration says it will leave TikTok ban enforcement for Trump [1]
Early Jan 18: Trump says he will 'most likely' give TikTok a 90-day extension to avoid a ban [2]
Late Jan 18: TikTok makes app unavailable for U.S. users ahead of ban [3]
Midday Jan 19: TikTok begins restoring service for U.S. users after Trump comments [4]
They already knew what was going to happen. They also changed the message shortly after disabling it from "We're working to restore service in the U.S. as soon as possible, and we appreciate your support. Please stay tuned." to "We are fortunate that President Trump has indicated he will work with us on a solution to reinstate TikTok once he takes office. Stay tuned!" [5]
[1] https://www.nbcnews.com/politics/joe-biden/biden-administrat...
[2] https://nbcnews.com/politics/donald-trump/trump-likely-give-...
[3] https://www.nbcnews.com/tech/tech-news/tiktok-makes-app-unav...
[4] https://www.nbcnews.com/tech/tech-news/tiktok-says-restoring...
[5] https://www.nbcchicago.com/news/tiktok-sends-notice-to-users...
(The latter part is probably because Tiktok's banning was not particulaly divisive within the population as it is in the US.)
Tiktok had a better algorithm (to get hooked) but Instagram eventually caught up (with algo)..
[1] - https://www.reuters.com/technology/oracle-prepares-start-shu...
From (2)(a)(1):
> (A) Providing services to distribute, maintain, or update such foreign adversary controlled application (including any source code of such application) by means of a marketplace (including an online mobile application store) through which users within the land or maritime borders of the United States may access, maintain, or update such application.
>
> (B) Providing internet hosting services to enable the distribution, maintenance, or updating of such foreign adversary controlled application for users within the land or maritime borders of the United States.
Possession of and providing non-distribution ( / maintenance / update) services to a "Foreign Adversary Controlled Application" are not in any way a part of the "Protecting Americans from Foreign Adversary Controlled Applications Act". Operative services are specifically and intentionally excluded from the list, to ease the burden of enforcement.
If not, what is your basis for your conclusion?