Earlier quoted context omitted.
That was a clearly partisan act Asking a customer to stick to the rules they agreed to and eventually ending the business relationship when the customer chooses not to is hardly a 'partisan act'. Parler could have just done what AWS asked (even temporarily, to keep themselves online while looking for alternatives). They didn't.
ISIS had Twitter accounts in which they showed beheadings and other things [1], largely as a recruiting tool in order to bring young Western Men to Syria to commit atrocities. "The Islamic State of Iraq and ash-Sham (ISIS) continues to use social media as an essential element of its campaign to motivate support. On Twitter, ISIS’ unique ability to leverage unaffiliated sympathizers that simply retweet propaganda has…
The difference is, there was actual moderation. Parler, a tiny (2 orders of magnitude tinier than Twitter) appears to have had no moderation infrastructure at all.
Even the data in your first reference seems to suggest that Twitter alone has probably moderated more accounts than Parler has actually had.