The first amendment allows companies to "censor people," that is part of the people's freedom of speech and freedom of association. It only prevents Congress from doing so.
If people want to advocate for nationalizing social media and forcing platforms to publish speech against their will, and making it illegal for them to moderate content, then they shouldn't pretend they're doing so in the spirit of the first amendment or what the founding fathers envisioned free speech to be.
It's a commonly spread fallacy that only "publishers" are allowed to moderate content, and "platforms" not. The entire purpose of Section 230 is to allow platforms to moderate user-submitted content without facing legal liability for doing so. Social media platforms have always been allowed to do exactly what they're doing.