While the Signal software itself is free software, my understanding is he trademarked the name Signal so you can’t fork it without rebranding it (similar to what Mozilla does with Firefox and Rust), and if you rebrand he forbids you from using the OWS servers.
Trademark is an entirely different issue from copyright and it’s my understanding that the trademark was the only legal avenue of attack he had against LibreSignal. Other forks of Signal such as Molly avoid using Signal’s trademark for that reason
He shut down LibreSignal: https://github.com/LibreSignal/LibreSignal/issues/37#issuecomment-217211165
While the Signal software itself is free software, my understanding is he trademarked the name Signal so you can’t fork it without rebranding it (similar to what Mozilla does with Firefox and Rust), and if you rebrand he forbids you from using the OWS servers.
Trademark is an entirely different issue from copyright and it’s my understanding that the trademark was the only legal avenue of attack he had against LibreSignal. Other forks of Signal such as Molly avoid using Signal’s trademark for that reason