Surveillance isn't the primary issue. INFLUENCE OPERATIONS is. China's ability to direct content to achieve their strategic goals, and to do so at a very granular level, is too great a risk. Its not the only property with this capability (cough, 4chan/pol/, cough), but its by far the largest.
Tiktok is not China, Tiktok is owned by a private company
All the arguments that you are using can be successful leveraged against any Inqtel funded private company (of which there are plenty), so I'd recommend you to speak in a measured way
Absolutely not. China is an authoritarian state with no rule of law other than what the CCP says goes. There are no meaningful firewalls between corporate operations and the Chinese government.