And in case anyone here doubts this is true, try using Google, Facebook or Twitter in China. It is absolutely possible for countries to block these services, including AWS or parts of it. Amazon has a duty to it's other customers to protect them from that sort of impact caused by the frankly unethical action of another AWS user.

This is a real shame and I wish there was a viable option open to Signal, it's an important app that provides a valuable service, but they really should have seen this coming.