China doesn't allow FB, Insta, Twitter, etc to operate in its market, but its companies can provide such a service to US customers? Is that not protectionism?
If we're afraid that China will use TikTok to push their propaganda in the US, we should be appropriately concerned that banning a platform to stop targeted speech is in conflict with our own norms around free speech. But instead insisting that TikTok can only operate in the US if FB/Snap/Twitter can operate in China on equal terms seems like it would be more in line with our rhetoric around wanting a rules-based international order, and freedom of both trade and speech under most circumstances.
If western social media companies were able to offer their services in China, their fear of our propaganda would be much worse than our fear of theirs.