It’s sad that people think this way. As a young child growing up in the 90s in a rural part of a small country, being able to access the “speech” of people around the world via internet forums was a revelation.
Are you really so scared of China that you’d throw that all away?
I think there is an aspect of foreign interference that Americans might be particularly blind to.
Namely, we are engaging in foreign interference towards any country that uses our social media (Mysterious Twitter X, Facebook, Youtube, et al.). Japan's online discourse lives and breathes Mysterious Twitter X, for example. We definitely influence and interfere in their domestic affairs whether anyone likes it or not.
If the sanctity(?) of domestic-only electoral will is paramount, it stands to reason that any and all social media should be legally barred from crossing borders regardless if that even makes internet sense.
If foreign interference in domestic politics is a concern, you absolutely do not want foreign-owned communication channels operating within you. They have every reason to manipulate discourse within them towards specific foreign ends in defiance to domestic interests.
TikTok manipulates discourse everywhere towards Chinese ends, X/Facebook/et al. manipulate discourse everywhere towards American ends.
This is an entirely separate concern from firewalls, which with the way you posited it might as well be a strawman.
Are you really so scared of China that you’d throw that all away?