Okuyama named his art Hakkoryu Jujutsu . . . I would assume. If he would have received higher level instruction in Daitoryu that may have changed things.
Okuyama's receipt of kyoju-dairi in Daito-ryu is nothing to sneeze at (given in absolute terms relative to the number of people Sokaku Takeda trained, this was a rare accomplishment), nor is the time he spent training directly with Takeda.
Also, a long-time publicly divulged core tenet of Hakkoryu's pedagogy is that "Hakkoryu unites martial arts and medicine so as to show clearly they are but one and the same". Given that Daito-ryu "aiki", as defined and/or expressed by any of the major legitimate lineages, is not reliant on shiatsu or kyusho-jutsu, it makes sense, as a licensed (Daito-ryu) aiki-jujutsu instructor, that Okuyama understood the difference between what he was teaching under Takeda's banner and what he planned to teach going forward -- and so chose his words carefully when branding his new art (of course, this does not mean that aiki was excluded as a notable aspect of Hakkoryu).