Re: Shiro Saigo with Sun Yat Sen (1913)
Judo: Self Taught in Pictures by Hubert Klinger-Klingerstorff / 1952
Pg 12 -- 13
Paradoxically it was a European who inspired the modern revival of Jujutsu in Japan. He was a German physician, Dr. Baelz, of Tokyo University, who took a course in the "gentle art" from the septuagenarian teacher Totsuka, and because he was so greatly esteemed as a university professor his students followed his example and took up the art of their ancestors. Once the renaissance had begun, it spread quickly, and eventually there were few Japanese who had not taken a course.
One of Dr. Baelz's pupils, Dr. Jigoro Kano, made a study of the various system of self defense, and came to the conclusion that all suffered from a lack of spiritual purpose -- the various locks and hold were learnt and used mechanically as physical actions.
The above is a short section from the said book.
Dr. Baelz studied Jiujitsu, kenjutsu, and kyudo. His autobiography tells of his time with the movers and shakers in quickly westernizing Japan, along with details about Judo and Jiujitsu. Various spellings of his name exist.
Baelz, Erwin. Awakening Japan: The Diary of a German Doctor. Indiana University Press (1974). Translated by Eden and Cedar Paul. ISBN 0-253-31090-3.
I need to get out more notes I took from his book (interlibrary loan), but it seems Dr. Baelz also was involved in setting up a competition with the new school "Judo" and a venerable JiuJitsu school. The Judo was soundly beaten. I'll look up the name of the instructor (who I believe did teach the police.)
So, just as Aikido downplayed its Daito ryu roots, Judo's overwhelming victory in competitive match with a police dojo may have not been (as your research has looked into.) I am also reminded of Funakoshi's likeness drawn in instead of Motobu Chōki when Motobu won against a western boxer in a match and they ran pics in the newspaper.
Back to Shiro Saigo and his Yama-arashi throw, this is a Daito ryu technique and even has a similar looking advanced technique in Hakko ryu (a derivative of DR).
I have written before on this technique and both have Obata's book with his version and also believe this is NOT the technique. Various old Judo books show a wide range of ‘versions' which are also not the DR version. Nothing new, just look at Sumo and similar but differently named Judo throws.
As to Saigo training with his ‘adopted' father who may or may not have taught Takeda Sokaku ‘aiki (and Takeda Sokaku did claim this to his son and other people), it is a matter best left to RESEARCH.