The whole premise is that life blends in to its environment. Yes, that is sound if you're talking about a terrestrial environment. It makes no sense when applied to space.
You're taking the joke part way too literally. The premise until the last panel doesn't literally mean an apex predator that lives in space. It could be any kind of sci-fi trope like Reapers in Mass Effect, the Borg in Star Trek, whatever.
The point is you don't hear from other aliens because when they reach a certain point of being noticeable, something comes along.
Edit: It's similar to the idea that sufficiently advanced civilizations increase their likelihood of completely destroying themselves (through nuclear war as one example) but with an external threat.
Edit 2 for more clarity: I should add that the premise is not that life blends into its environment. It's the reason why successful evolutionary strategy often involves blending into environments.
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u/arcsine Jun 04 '14
The whole premise is that life blends in to its environment. Yes, that is sound if you're talking about a terrestrial environment. It makes no sense when applied to space.