Right but that’s fragile. All it takes is one group to break the ice and suddenly they’re all talking.
Also, is the theory that we could live in a dark forest because every single species is insular enough to be afraid of such a threat? That means they all have to believe in the threat and yet also no species is aggressive enough to become the threat. But none of them thinks, “Wait, either we’re alone or everyone is hiding. If everyone is hiding, then the threat can’t exist, so we may as well say something.”
Again, it’s fragile. I find it completely unconvincing.
The Prime Directive concept is way more believable to me, as is the idea that life is just sparse.