The article is kind of a mess. The timeline is wrong.
It also confuses the Tenyukyo with the assassination of Queen Min, and they weren't even in Korea at the time.
The Japanese minister to Seoul at the time of the assassination of Queen Min by a motley bunch of Japanese thugs and continental ronin was General Miura Gorô, who was later the head of Gakushuin when Kanô shihan was there. There was a bizarre trial in Hiroshima of Miura and a bunch of Japanese involved, and despite mountains of evidence and some direct testimony, they were all acquitted.
Uchida Ryôhei wasn't even in the Korea at the time, I think he was in Siberia. He had no involvement, wasn't put on trial; he showed up in Korea much later, foisted off on Itô Hirobumi, the Japanese minister, as a member of the staff, against Itô protests. Essentially he was given official cover status for his acts as an agent provocateur.
I think the info about he and Kanô shihan setting up the first judo dojo in Kyushu is wrong, too. The first pure judo dojo I know of in Kyushu was in Kumamoto at the 5th High School were Kanô was the headmaster from early 1890s; and Kanô brought his own instructor, a very early Kodokan student named Arima Sumitomo. But judo was being taught in the Fukuoka dojo associated with the the Gen'yosha much earlier.
Having said that, Uchida was a noted judoka. It was said that he was the fiercest fighter in practical, street fighting judo, and no one could best him as a young man.
Both Uchida and Arima wrote the earliest judo books: Kanô shin wrote forewords to both.
The Kodokan now points to later books by active Kodokan instructors as the earliest judo books, but Uchida and Arima record the earliest days of judo, including finger and leg locks, striking, etc. Arima's last book, actually edited by his son after his early death , was in print from 1904 until the mid-1930's. Uchida's books on martial arts are still available in reprints.