AWS is a private business, they don't have to host anything they don't want to. Forcing them to host parler would be an egregious violation of their right to choose who they associate with.
I think a way more interest question is this - what about modern US conservatism makes violence so attractive to it? You cannot have a conservative forum that will not rapidly devolve into violent threats. Even /r/conservative, the more mainstream and mature conservative subreddit is absolutely full of people threatening revolution, backs against the wall, etc.
The reality is that we as a society are getting numb to this and are actually being far too tolerant.