This is -of course- well in keeping with his then current training in Daito ryu - where aiki is a separate discussion from technique. For similarities in dairies and notes; you had Sagawa's father enter in his own journal in 1913 "Sensei says to apply aiki-here."
There are prescribed methods for applying aiki in different ways, but aiki emanates from aiki in the body as the first requirement. Also mentioned in Sagawa's own book.
This is just more reasons why people like Stan, Ellis and myself say you really cannot discuss Aikido without discussing Daito ryu. The cornerstone requirement of "aiki" is foundational and inseperable between the arts; it is what happens after aiki is applied, and the depth of the abiity to generate aiki that is the defining difference. But even now, in the 21st century, we see so many in aikido really striving to go back to the older methods of application (which I still feel is mistake and a digression from the path of aiki) if it is done without training the body -for aiki.
One correction. It was -of course- Kodo Horikawa's Dad (Taiso) who's journal recorded that training note, not Sagawa's Dad.
I was rushing out the door when I wrote that, It doesn't take away from the point, but it worth being accurate.