There's also the Section 702 angle... US can get all US social media to spy on non-US citizens without anything in the way of legal pushback.
US citizens have rights. Non-US citizens, do not.
I think the problem with TikTok under their audited, non-interference under their Project Texas is... That they might not easily hand over data, or suppress views that US Gov isn't a fan of.
Which will change once TikTok is owned by a US company.