Not just another country, but a hostile foreign country. If France owned TikTok no one would care. But to the US government, China is in the top 5 of most hostile nations and is definitely the top of hostile nations in terms of world power and reach. It's essentially giving out a LOT of info to what they see as "the enemy". And also it has a lot of potential use to track US government employees like diplomats and high-level military leaders. Even if those people don't have TikTok installed, their kids might.