Seems to me it's only guilty of the same data scraping for marketing purposes that Meta is... maybe even less so as I always found TikToks advertising less gross than Instagrams.
Both suck but TikTok is slightly less suck.
Is it really a security thing or is it a "We are getting pressure from US companies to remove competition" thing?
Tbh it's all just a result of Facebook lobbying of the same variety that killed Vine. Lawmakers just had an additional sinophobic angle to grandstand on this time but the material origin has nothing to do with natsec.