This is like not seeing the difference between allowing anyone to drive on a public road verse forcing everyone to pick up all hitchhikers.
I just feel that the issue of blocking a particular site is tangental to the real issue of the power these companies have. I am much more worried about the way their algorithms work for choosing who sees what, but that is not a concern based on 'free speech'
Social media is the tool, and some uses are ok and some aren't. I am not 'showing my true color' when I condemn someone who uses a knife to murder someone, even though I praised a master chef's use of a knife to cut food just the day before.
The government telling me, the hypothetical Twitter CEO, that I am legally mandated to publish your tweet, be it actually misinformed or just plain unpopular, or face asset seizure and jail time as a consequnce -- that is an _actual_, real infringement on free speech.
It just turns out that a lot of those SV libertarian free speech absolutists were actually partisan authoritarian hacks that are now abusing the notion of free speech in the current online discourse, so that the government will step in and mandate publishing their particular flavor speech. The people arguing against Twitter having the ability to silence and ban accounts (for any reason) are arguing for a Propaganda-class of speech that must be repeated by all who have any influence.