> While it regularly publishes the code of its client apps, it hasn't updated the Github repository for its server for almost a year.
Last commit was 5 days ago: [0]
As for not playing nice with third-party clients, I can give you that point.
[0] https://github.com/signalapp/Signal-Server/commit/365ad3a4f8...
It's practically a principle of the Signal project to discourage third-party clients. Signal's security work is done, for obvious reasons, mostly clientside. If you have a diversity of clients, you're stuck with the lowest common denominator of mainstream clients. Without them, you can roll out any feature you want to.
So why doesn't Telegram have the same issue? Just like Signal, the client is fully open source and most of the secure bits are client-side, but unlike Signal they make no pretenses about being "fully" open source as they've never published any server sources, nor they make hostile moves towards blocking third-party client interoperability.