This isn't a technology problem / solution. It's a people problem. Parler refuses to moderate hate speech / violence, instead choosing to selectively moderate,

This isn't a technology problem / solution. It's a people problem. Parler refuses to moderate hate speech / violence, instead choosing to selectively moderate, similar to a white supremacists message board / etc. Amazon, et. al. don't host those kinds of sites, and Parler is no different.