Signal should be federated. This censorship problem would not exist, or would be organically routed around, were the service federated. Without federation, Signal is just another stepping stone in the long path of eventually abandoned instant messengers, all the way back from ICQ. We will get to an SMTP-like protocol, and email-like service, at some point. If not Signal, some other one.
Do any SMTP servers still allow organic routing? I was under the impression that all modern servers have extremely cumbersome auth/dkim and its hard to not be GMail and still send a real msg and have it arrive