Okay, okay . . . he wrote in kana in an attempt to prevent the possibility that Takeda's Korean house boy might read the text (It was rumored that some Koreans were literate.) and use the privileged information to assert a claim that he (As far fetched as it sounds.) actually observed, and even learned the Great Eastern Art. Worse still, if Tanomo wrote the characters in Chinese (Some Koreans could read Chinese since they had the misfortune of living nearer to the Chinese than they did to the land of the Kami), but of course they needed to be trained to read Chinese in the proper Japanese manner.), the house boy in question might use the same characters to, eventually, name his variant art, only pronouncing it (As outrageous as it may sound.) in his NON-Japanese Tongue. Oh the shame, the Great Eastern Art pretending to be practiced by a non-Great Eastern people and naming in the manner of some upstart offshoot, it boggles the mind . . .better to write in kana and prevent the whole problem from the outset!
He was a Shinto Priest right? Better to not pollute pure Japanese arts with foreign influences. Stick to good ol home grown kana, the stuff of Kotodama!! Oh, and repel the barbarians and up with the Shogunate. (He was an Aizu Shinto Priest after all!)
Nothing good could ever come from writing
. . . dough!
(Only one glass of wine for that one!