Well, if a mastodon instance admin decides to ban you, that's their personal decision. You can go to another instance.
If another user blocks you, that's on them but you have no right to push your messages into another user's home system.
If all else fails, you can host your own. It's ultimate free speech as intended and as someone who hosts a mastodon instance, it's a system that works pretty good, there is no noticeable hatespeech in my federated timeline.
edit: I might have misunderstood the GP, but I'll let the comment exist. Banning mastodon in the US is a non-concern since it's a french open source development.
I think tokamak meant they will be banned by law, which sadly I can see happening - it effectively happened already with napster and bittorrent in some jurisdictions.
I can't. Napster was shut down for copyright infringement. Bittorrent is blocked in some places on similar grounds (although, notably, BitTorrent itself is still alive and well - the law enforcement action has been against distributors of copyrighted materials and sites like TPB).
But even if someone really wanted to get Mastodon banned and created a server full of illegal material to give politicians the fuel they'd need, the law enforcement answer there would be to go after that host. The overall network would not be liable because it wouldn't be hosting/distributing the material.
Once the illegal activity is defined as running the software itself, because it cannot be done legally, then all hosts become liable, regardless of what they host. Simply by launching it, you would have broken the law.
To fight this, please use Mastodon and/or create an instance in it. It must become as widespread as possible to become the norm, then it cannot be (easily) banned.
The authoritarian stream in the EU are already working on something similar, but it will be a much harder sell and i still hope we can stop it, before it is too late.
I fin it very unlikely to see distributed social networks like Mastodon or Diaspora completely banned. In the US, this should be protected under the first amendment, in many other countries, it's protected under similar laws. And many countries don't care as much about violating their citizens' privacy as the US does.
If another user blocks you, that's on them but you have no right to push your messages into another user's home system.
If all else fails, you can host your own. It's ultimate free speech as intended and as someone who hosts a mastodon instance, it's a system that works pretty good, there is no noticeable hatespeech in my federated timeline.
edit: I might have misunderstood the GP, but I'll let the comment exist. Banning mastodon in the US is a non-concern since it's a french open source development.