Amazon included some screenshots of content from Parler that they said violated their ToS. I'd say look at the screenshots they provided then try to justify hosting that content:
https://www.buzzfeednews.com/article/johnpaczkowski/amazon-p...
https://www.buzzfeednews.com/article/johnpaczkowski/amazon-p...
This whole banning of Parler looks like a bad faith exercise where those with different political opinions are held to stricter standards.