Censoring is different to banning though. Banning in this case is the correct word to use, censoring isn’t. You can censor things on a platform, you can’t censor a platform entirely - that is a ban.
The censors in this case are Apple and Google, acting at the behest of the US Government. This news isn't about Tiktok censoring, rather about it being censored. Apple and Google are the platforms/publishers.
(There are also a whole host of other service providers that might be put into the position of being censors if Tiktok were to ignore the law and continue working for sidedloaded apps).
