I wonder what's the significance of using kana for the worm. Agreed that the text itself makes clear that the worm is just an example, not itself important.
Morihei Ueshiba cribbed quite a lot from Deguchi, but I think you need to look at Deguchi's writings to see how much. Deguchi wrote a lot -- and I mean a lot. He was also an expert at metaphor and word-play, which Ueshiba would have understood.
As for katakana, for a start you have Inoue quoting Shioda quoting Uesiba -- which is then published / edited by Jiromaru or the publisher's editor. When I was preparing TIE 25, I came across the word saniwa
, which was one of the terms used in Omoto to designate the mediator, or go-between, between a medium and the spirit that possesses the medium. This is a case of kamigakari
, but there are other terms used also. There are a number of ways to write the noun saniwa
in Chinese characters, but Ueshiba used the katakana サニワ and he also used it as a verb, as in saniwa suru
. He seems to have used it to denote one's accurate perception of the physical/psychological state one is in.
There is so much, which M Ueshiba takes for granted, that we do not know. I was quite astonished, for example, to read about Kawatsura Bonji and his theories of the soul. It makes the mediaeval scholastic discussions about angels on pin-heads light reading by comparison.