The way TikTok manipulates its feed to serve the CCP's interests and influence public sentiment in the country is a threat. Things like downplaying the CCP's invasion of HK.
https://stratechery.com/2020/the-tiktok-war/
That's basically the opposite of what's happening here. TikTok's threat is foreign government manipulation of the public and the block is blocking that government manipulation.
Here if Twitter got blocked it'd be because they refused to implement the government manipulation - it's a difference in kind.