Marco Rubio asked the Committee on Foreign Investment in the United States, to review TikTok’s acquisition of rival app Musical.ly. The impetus seems to have been a Washington Post story that ran that September[1] that questioned the absence of Hong Kong protests on TikTok in contrast to other social media platforms.[2]
Also that same month Chuck Schumer and Tom Cotton sought to have the US intelligence community assess the national security risks of TikTok(and other Chinese-owned platforms) sighting concern about election meddling and influence.[3]
[1] https://www.washingtonpost.com/technology/2019/09/15/tiktoks...
[2] https://www.theverge.com/2019/10/9/20906971/tiktok-censorshi...
They talk about ‘freedom of speech’ in TikTok which first of all for its US operations, it doesn't apply to private companies like TikTok, FB and Twitter. However the censorship case is far much worse. Anyone who appeared ‘Ugly or Poor’ was censored [3], they ‘apologised’ for censoring BLM posts on the platform at the time calling it a so-called ‘Glitch’ [4] and still actively censor activists or anything against the CCP in order to comply with its censorship laws.
If anything, TikTok is far from being a platform to supporting this ‘freedom of speech’ if that ever ‘existed’ before it rose to prominence [5].
[0] https://edition.cnn.com/2020/07/10/politics/dnc-warning-tikt...
[1] https://www3.nhk.or.jp/nhkworld/en/news/20200728_39/
[2] https://www.abc.net.au/news/2020-08-02/tiktok-under-investig...
[3] https://theintercept.com/2020/03/16/tiktok-app-moderators-us...
[4] https://time.com/5863350/tiktok-black-creators/
[5] https://www.cnbc.com/2019/11/26/tiktok-says-it-doesnt-censor...
Viewpoint discrimination is against the first amendment. We know Trump wasn’t offended by the idea that foreign countries might be trying to help him get elected, and has repeatedly called it a “Russia hoax”, but now that a social media app has anti-Trump users it’s suddenly a national security threat without any evidence provided?
Huh? Where on Earth did you get that idea? From what I've read and observed, it seems like while they may not be self-identifying as "liberal" or Democratic on quite the same level as Millennials, they still seem to hold views which are far from what you'd traditionally call "very much to the right".
https://www.pewsocialtrends.org/essay/on-the-cusp-of-adultho...
https://www.businessinsider.com/gen-z-changes-political-divi...
And the President has the right to ban companies on national security grounds as well.
The legal basis for both is very well founded with plenty of precedent.