Comparing tiktok to the post office circa 1940 is… an odd choice.
Tiktok is more like a foreign power owning playboy and mad magazine. People making dumb videos for a laugh isn’t critical communications infrastructure it’s entertainment. Banning ZTE and Huawei makes sense… but if your culture and infrastructure is so sensitive that Chinese ownership of dumb entertainment is a threat… you’ve really already lost.
If tiktok as foreign spyware is a problem, ban the mechanisms of surveillance, everyone does it and it’s not only a problem when China is in control of the data.