If Parler violates the ToS then Twitter surely does as well. But, since [0]Twitter pays Amazon an obscene amount of money they are immune. Facebook is in a similar position where they've been [1]enjoying the rewards of 'selective non-enforcement' for a very long time now.
I probably disagree with just about everything ever said on Parler but it's difficult not to point out this absolutely reeks.
[0]https://www.bloomberg.com/news/articles/2020-12-15/twitter-w...
[1] https://www.cnbc.com/2021/01/07/capitol-riot-a-rocket-ship-f...
EDIT - I can't tell if the downvotes are people mistakenly believing I'm defending Parler or because they believe that $Big_Tech is free of blame.