I really have no problem at all with site owners or operators deciding what content they do and don't want on their site when accepting third-party contribution

I really have no problem at all with site owners or operators deciding what content they do and don't want on their site when accepting third-party contributions, it's when the (US) government is involved in directing or influencing that censorship that it becomes a problematic "end run" around citizen's rights. The regulation needs to be directed at the government agencies who are secretly conducting public business through private channels and violating the rights of citizens through warrant-less monitoring, illegal censorship, and - though currently not illegal or otherwise proscribed, still very problematic - discourse shaping and propaganda spreading. A company spreading propaganda is advertisement, company censorship is curation, and a company spying is market research. A government doing the same things, whether using a "corporate condom" or not, is just propaganda, censorship, and spying, and taking advantage of private businesses to sidestep the Constitution should be dealt with in the harshest fashion if democracy and civil discourse are still valued by society.