Originally Posted by
Petrikow
This is pure speculation, but it might have something to do with Chaos' meaning as "primeval".
For someone like Shiki who can see the end of all things, the pure "beginning" is something he shouldn't be able to perceive.
For the record, 混沌 (the word used here) has the same kind of etymology as Chaos does in western languages. It is the primeval state of the universe, before its creation, in Chinese mythology. It was later extended to be used for the modern meaning of chaos as well, in mimicry of the western tradition.