I’m not qualified to determine personally the situation of signal, or any other app. But I don’t need to. There are several experts who are and the fact that multiple of them have analyzed and evaluated an app as signal should give us a lot of confidence in their conclusions.
We need to trust experts, and I don’t mean individual experts, but the experts as a whole, especially when they verify each other’s work. This is what it’s about. You can’t do everything yourself, you got to trust some form of collective.