We're banning the company not the ability to express. They can upload the exact same videos to YouTube shorts, Instagram Reels, and who knows how many alternatives.
This is the foundation of reciprocal trade agreements: We don't put tariffs on your cars if you don't put tariffs on ours. We don't ban your social media companies if you don't ban ours.
Unless China is part of the US, I don't see how CCP/Bytedance can get First Amendment protection.