It seems like the proposed cosmological natural selection is fundamentally different from biological natural selection in the sense that there is no actual pruning. That is to say that given a universe all of its children will survive and reproduce based solely on their laws of physics, independent of what all the other universes do. This would mean that all possible universes which could be reached through this mechanism will be reached, wheras in evolution as it happens on Earth, most of the potential organisms never exist because there ancestor got out-competed at some point.