Autonomous systems don't depend on a default route. It's not difficult or expensive to set up a BGP router. The labels attached to these contracts and agreements are really beside the point. If you want to play the Internet game then it's worthwhile to play it as an equal. If you host your business in the cloud then Amazon has shown us today that they will delete you like a bad YouTube comment the moment people weep and wail on Twitter.
If you're going to do something like parler, your own tin, in your own building (with a contract that doesn't refer to any acceptable use), your own network range(s), your own AS, and fibres conncecting to multiple POPs.
Fibres and building contracts typically don't allow the service provider to cancel except for very specific cases (not paying the rent for example), and are long enough that alternatives can be sought ahead of schedule if the company no longer wants to deal with you.
