User blog comment:James12708/Reapers VS. Forerunners VS. Angels from Darksiders VS. Humanity from Halo VS. Council and humanity from Mass Effect VS. Imperium of Man/@comment-50.80.96.33-20130111215612/@comment-2250460-20130111223315

What? Indoctrination isn't something you can just "block", at least not without prior knowledge of it. The Reapers are an unknown, the Forerunners would have no way of knowing.