Their personal data won’t be kept away from the CCP. People that use TikTok will use VPNs to do so if needed (TikTok also would no longer have to listen to the US government, probably intensifying the data collection), and otherwise the CCP can just purchase (or steal) the data from US data brokers, because those are still very much legal. Did we forget about Cambridge Analytica, where an adversarial foreign government used our own domestic companies against us?