Somehow all those theorists imagine the space civilization that likes to kill - yet has not discovered any ways to find something killable. So the apex space predators hope that the prey will send the signals into space. That's how they became the killing machine - by never searching.
This also reminds me of the catch 22 of space colonization - the civilization whose genetics promote conquests and colonization will most likely kill itself in internal wars way before colonizing any noticeable part of the space. And peaceful civilization has time to grow to power but does not have colonization needs. The space predator civilization will most likely die in nuclear war before they have chance to gather together and make peace to pursue space colonization as one.