Yes, China does censor sites and apps. But is it really good to censor sites and apps just like they do? Aren't we better than that? Do we want anyone having that sort of power?
I believe the national security risk argument is stronger in the case of Huawei. Since having a state run company build essential communication infrastructure is clearly a bad idea. However, I think it also applies to ByteDance. Why would you allow a foreign government uninhibited access to huge amounts of data about your citizens? Especially when that government is a hostile totalitarian regime currently engaged in serious human rights violations.