Where I live, while the use of leased property in various unacceptable and/or illegal activities is a basis for canceling the contract and subsequent eviction (among other reasons more directly relevant to housing), one generally needs an order of court to evict a tenant if they protest. This applies to both housing and business proprties, though people's homes have greater protections.

Also, in some situations here the landlord may lose the grounds to proceed if they won't press the issue as soon as they become aware of it. This is exactly to avoid situations where the one side arbitrarily decides throw the book on whatever the other's activities they can pin down on them.

(Whether the comparison is adequate depends ofc if AWS has consistently made complaints to Parler about the objectionable content. Their message included a part where they pointed out they had requested moderation action earlier, so I suppose they have.)

I can see the issues relevant to cloud hosting are different enough so that analogies are not 1-1 anyway. In general, it is a good principle that content that encourages violence and other illegalities is removed from the public. It would be still also a good idea to have procedures where the hosted party could protest if they are engaging in illegal acts or other breach of contract claimed by other party and the enforcement is applied equally.