Like I said before, the notion that it was not included in the Daijiten because it was banned. Would make perfect sense except for the fact that a bunch of Kenpo-teaching "ryu ha" are included in the Daijiten along with their lineages etc. So that would mean that the ban was lifted during the time that this stuff was recorded.
That is why I went down the path I did because if Mitose learned Yoshida Ryu martial arts and taught Kosho Ryu Kenpo. Plus, Yoshida Ryu is not mentioned as teaching any Kosho Ryu Kenpo in the Daijiten but the Daijiten does mention Kosho Ryu just not as a Yoshida system then its possible that either:
1. Mitose studied 2 systems, Yoshida Ryu and Kenpo
2. Yoshida Ryu's Shinobi art contained Kosho Kenpo
3. Yoshida Ryu's Aikijujutsu contained Kosho Kenpo
5. He simply felt that the Yoshida Ryu Shinobi or Aikijujutsu system was good but Kenpo was better for self-defense and easier to teach as it did not rely on throws as much as strikes to the nerve centers so he switched and adjusted his system and created Kosho Ryu. It was aknowledge as a legit system of Kenpo by the Koryu people but not in the Yoshida line. In its own line all by its self without a lineage because it was new.
To be honest the 5th one seems like the most logical when you think about Mitose's choice to serve the US instead of Japan and his book and the nature of his techniques and philosophy and it still takes into consideration his connection to Yoshida!