Comment by fsflover

> Even if NSA ignores those rules, they have literally no rules about compromising foreign servers

This is not good enough. Signal server is a single point of failure: NSA (and any other attacker, e.g., China) knows that the users can't go elsewhere, so it's very easy to target them all (thanks to the Signals's politics of walled garden). In case of Matrix, there are thousands of servers around the world, which you have to find and get into. They can run completely different software. This is not very scalable or easy.