Slippery Slope means just that, persistent and constant escalation of censorship which is exactly what is happening right now. Amazon jumped on the bandwagon behind Google Play and Apple store and Twitch and Facebook for internet SJW points and to not be left behind in the "I don't like what they say" Olympics.

I don't particularly agree with the messages of Parler or lean right at all, I am a staunch libertarian and believe that any and all opinions should be heard.

"Once a government is committed to the principle of silencing the voice of opposition, it has only one way to go, and that is down the path of increasingly repressive measures, until it becomes a source of terror to all its citizens and creates a country where everyone lives in fear." - not sure who to attribute it to since I don't know, but it is almost certain this censorship wave was started by a political party for political goals. The end result is the same.