User blog comment:Differentdrum/Things that make me go Hmm..../@comment-5619706-20131029011034

Time travel is a concept that has almost always caused plot problems, not just in SpN but in other literature as well. It's really confusing and difficult to get everything straight. Sometimes, it's best to just suspend disbelief.

Sera Gamble was leaving SpN and most likely wanted an easy way out of the Leviathan mess she wrote (don''t get me wrong--it's great in theory, but they were badly handled and as a result, they just turned out to be really bad instead of badass) so they just gave a flimsy and lazy explainer that "cut off the head, and the body will flounder"--both literally for individual leviathans (decapitation), and figuratively for the collective of their species (Dick's death caused all Leviathans to revert into just some other low-level dumb beast that could easily be hunted).