> violent overthrow of the democratic process
Trump did not advocate for a violent overthrow as far as I know.
> I consider a free society to be a competitive marketplace for ideas
That requires those ideas to be heard. If everyone segregates into their own political bubbles there will be no competition of ideas, just endless echo chambers.
> It's not and whatever the concept of "social monopoly" is can only make sense if there is one party controlling all social expression, which is obviously not the case
Eh?
The people controlling the big corporations that control most communication in the English speaking online world are of very particular political leanings. They might not control all expression but they certainly control most of it.
> But political views are not (and IMHO should not) be protected. This would be the equivalent of picking winners in the free market of ideas.
I don't see how preventing the silencing of some ideas is equivalent to picking winners.
I'm not necessarily saying political views should be protected, just disputing the validity of your logic here.
> That many independent organizations came to the same conclusion is evidence that the system is working and that the idea itself has failed in the marketplace of ideas.
You say "independant", but there are strongly dominant cultures in those organizations and the people admitted to them are from a specific subset of the population. They might be somewhat independant in that Facebook doesn't decide what Twitter does (though I expect there's cross-polination of people moving back and forth between them), but they're both drawing from mostly the same pool of people and ideas.
I expect that Trump supporters, for example, have little influence in Facebook the company.