I think the argument thrown_22 is making is that Americans would be less worried if it was Vine instead of TikTok because Vine is made in America. Tiktok is a globally relevant social network not only not from America but from what is increasingly seen as America's rival.

The argument isn't inputting on the value/harm done by the social network but rather the perception of that value/harm which is influenced by the sense that TikTok is foreign in a way Vine was not.