'Violence' is probably being planned on Facebook, Signal, text messages etc etc by all sorts of 'evil doers' to quote GW Bush.
This doesn't mean you ban the medium. section 230 defines bigTech as platforms, not publishers. You don't close down AT&T because someone organized a punch up via text messages.
All reports of activity on Parler seem to indicate it’s basically a breeding ground for right wing extremism, so I think it’s incumbent on you to show why it’s more like text messaging than the aforementioned gang bar.
That said, Parler is not being shut down.
Also, Section 230 has nothing to do with AWS’s relationship with Parler.