Parler just got ejected from the internet. Is it totally unthinkable that they would have adjusted their behaviour and moderated whatever Amazon had told them to if given, say, 2 weeks notice? They probably would have, then transitioned off AWS in an orderly fashion.
I mean, AWS basically took their business under false pretences. AWS wasn't trying to provide them a service, it was trying to kill their company.
Parler knew the terms when they signed the contract and didn't bother to adhere to them. They had months of notice. AWS did wait until Parler became completely toxic to enforce the terms, but they had lots of cause available.