In a recent article in this journal, Lingam and Loeb developed an excellent heuristic for searches for biosignatures versus technosignatures. We consider two ways in which their approach could be extended and sharpened, with focus on durability of technosignatures. We also note an important consequence of the adopted heuristic that offers strong support to the ideas of the Dysonian Search for ExtraTerrestrial Intelligence (SETI).
Keywords: Astroengineering; Dysonian SETI; Extraterrestrial intelligence; Fermi's paradox; Galactic habitable zone; Kardashev's classification.