Super-predator Civilizations solve the significant problem of blaming the silence on a psychological quirk rather than statistics.

When you are making assumptions about the millions of civilizations, it is absurd to think they ALL retreated to playing video games for eternity, or ALL nuked themselves to oblivion.

With a single super-predator civ, that has a huge leg up on everyone else, they can have unusual motivations, and techniques. The problem with a super-predator is you likely won't be able to learn anything to prove or disprove them until you meet them, with all that implies.