People saying parler has a right to exist should be asked if they feel aws, Apple and google should also be forced to host an ISI chat forum. Or if they only support terrorists seeking to overthrow the democratically elected government when it suits their personal politics.
Either they support de platforming terrorists, or they have to afford these companies the same level of selectivity they are themselves displaying. In either case you have to allow these hosting providers to say “no way, we aren’t touching this”.