In theory, I ran a platform that protected everything the First Amendment did, and protected nothing that the Amendment did not protect, I should be legally in the clear.
But I'm not going to attempt such a thing - because it's clear Congress would do the ultimate shakedown.
Let me break this down for you: you host a weekly poker night. My buddies and I come and during these nights plan a crime. We than carry out a crime and get arrested. The investigators come to you and ask “what did those guys talk about at your poker nights?” You say “poker stuff”. They subpoena you to get a better answer. Where in all of this did the first amendment come into play?
Sure except the subpoena in question was not actually about records of conversations that the rioters had, it was about efforts FB did/didn't take to discount election misinformation.
Election misinformation is covered by free speech.
In the same way as yelling “fire” in a theater.
Not at all? There's a clear moral (and certainly legal) dividing line between the two.
As other have said, this is a bit different then that since it's an investigation but I'm sure you can find some examples from the past years of politicians and government officials trying to influence moderation policies for better or worse.