For strict constructonalists, the Constitution only protects speech as being free from governmental interference. Otherwise speech is not free from consequences. The courts again will not save us.
There's the rub.
I gather that Amazon's argument for "suspension" is based on it's duty to the commonweal--to stop the bloodbath of an insurrection being promulgated from its --tenet, Parler.
This is an exaggeration to explain a subtle but critical undercurrent in the arguments.
Parler's response:
"BS, section 280(?) indemnifies you from anything my people, or even your people say! You are under no threat at all!"
"And another thing: I see that coat-hanger halo you perched on your head! You got some nerve, saying you screwed me so that the masses could be safe!"
"Who the hell do you think you are, declaring yourself protector of the people? That's the government's gig! And we got plenty of gov thank you!"
This last part could bring the issue to head--can companies providing services like web-hosting become the Sunday-school teacher washing kids mouths with soap--a job the government has gradually dropped over the last 50 years.
Can Amazon say "well somebody's gotta do it"?
This much seems undeniable--Amazon was in no danger of liability or any other kind for anything Parler did or said.