[tptacek]

What's stopping you? What does that have to do with having a bit-for-bit identical version to what Signal is running?

[hoophoop]

...the simple fact that there's no guarantee that either the server or the client would receive updates.

That means hard-forking the old server and client and maintain them as an independent project forever.

That's what's stopping me and many other people from creating a community and federated version.

[tptacek]

Any independent server is of necessity going to be an independent project forever, so I'm not sure what your difficulty is here.