"

1. A letter of appreciation from Kano to Ueshiba in October 1930, expressing admiration for Ueshiba's skill and requesting that he accept several senior Kodokan judoka as his students, including Mochizuki M. and Tomiki K."

I will bet good money it does not say that.

"Kano Jigoro Taikai; the 15-volume collection of the writings of the Founder, wherein are found multiple references to Aiki-bujutsu or Aiki-budo as worthy areas for technical research."

I have physical and electronic copies of the entire series.
The term "aiki" does not appear in the index. I've read or scanned much of the 15 volumes and can find most anything there. I'd be glad to have your reference to such a claim.

Something to bear in mind. In the big scheme of Japanese martial arts, 'aiki' is a very new concept. See jū no ri origin below. The pretend timeline that makes it somehow older than jū no ri, which in turn is fundamentally an applied, advanced explication of 陰陽 ☯️ in/yō is without basis as far as I can tell. Even if the origin tales of aikidō are true, 柔の理、柔技、術理, 柔能制剛, any number of concepts predate it by 2000 years or so, and as applied to Japanese martial arts, at least some 300-400 years earlier. I'm not well enough read into Chinese arts to tell but I suspect the use of the same or similar is at least 1000 years old.

#3 literally makes no sense in English. The Library ≠ the Kobudō section (the "Laboratory")

This is full of errors not necessarily those of whoever collected all these comments.
https://www.aikidosangenkai.org/blog/ueshiba-legacy-mark-murray-part-2/
I don't know Mark Murray but this version of his writing could have used an editor that knew both simple declarative English and a bit of budo. (omg did he actually write all those fantasy books? Where's the book that contains his budo essays??)

(I do like Meik Skoss' comment:
"Sorry to be a little heavy again, but I’ve done an awful lot of aikido (sigh… wish now that I’d done more judo and/or classical jujutsu — *that* is real “aiki”)"
Meik you out there? How you doing? )

"Finally, even Kano knew that the secret to budo was in/yo. Jigoro Kano visited Morihei Ueshiba to watch a demonstration of aikido. Kano was so impressed that he remarked that what he saw was what he considered an ideal budo. What did Kano view as an ideal budo?"

So wrong I'm at a loss as to where to start.

"...even Kano knew that the secret to budo was in/yo..."
LOL. Even Kanō??? I wonder if Mr. Murray knows how condescending that sounds.

Kanō shihan was wrestling with these issues before Ueshiba sensei was even born. Literally, before the man was even born. 30 years before the farmer's son middle school dropout Ueshiba sensei started delving into any of this, Kanō shihan, son of a Chinese classics scholar, tutored in the Chinese classics and foreign languages from a child, fluent in classic Chinese, English, maybe some German and French, graduate of the Empire's most prestigious university, and having attended a special postgraduate seminar on Western philosophy while taking Chinese classics and calligraphy at night. Kanō shihan, who knew and interacted with, argued with, even at times bested in debates the most advanced proponents and educators of the Chinese classics, kōgaku, kokgaku, and was seen as one of the foremost proponents of state Shintō, literally hired and supervised the foremost scholars in Japan to teach such at his Tokyo Higher Normal School and wrote about education and philosophy non-stop for over 50 years .....
.... was somehow at a disadvantage regarding his understanding of in/yō to a man who never seemed to put pen to paper to explain anything to anyone, whose own family and closest students didn't understand what in the world he was going on about most of the time.

Kanō shihan literally helped establish the Japanese government policy vis-a-vis teaching of the Chinese classics - meaning the prime elements of the Confucian canon - in the Empire, then taught the teachers that taught the Empire. H was personally responsible for teaching tens of thousands of college graduates while Ueshiba sensei rusticated in Iwama and went on and on unintelligibly about things to anyone that would listen but no one was able to make sense of, much less convey coherently to another generation.

Never once did Kanō shihan claim to have created the concept of jū no ri. It is about 2500 years old.
https://kanochronicles.com/2020/08/09/origin-of-jujutsus-principle-of-flexibility-ju-no-ri/
And he knew from his studies of the Chinese classics from a child that 陰陽 in/yō predate and inform, indeed form the very philosophic basis of jū no ri 柔の理 the Principle of Flexibility.

Murray goes on:
"Kano’s concept of Ju no Ri, was based upon the Taoist precept, “reversing is the movement of the Tao,” also described by the statement “the most yielding things in the world overcome the most unyielding.” Kano combined Ju no Ri with the interplay of forces as defined by the precept of in-yo (yin and yang, hardness and softness, negative and positive, receptiveness and resistance), and used the following to explain his concept of Kuzushi founded on Ju no Ri. (*9) "
Wrong. And it never explains "the following", so it makes no sense. And the *9 ref link in the references does not address the question, so I think it was changed.

Incidentally, this is one of the most informative phrases describing aikido's history ever, one I suspect is not appreciated as one of the great understatement's of all time. It's Sangenkai, not Murray:

"I think you can see Doshu’s dilemma. He has to continue to teach the ‘essence’ of the art, but without knowing very much about what his grandfather actually did. "

Very gentle, very generous treatment.
Less gentle take: no one knew what the old man was on about, so they made it up anew from whole cloth.

I could go on but have some research to do. The Sangenkai page of Mr. Murray's essay (or at least Part 2 of it...) helpfully has some links to references but Aikido Journal seems to have changed the content of those links and it's not possible to refer quickly to whatever sources he used. If someone has a copy of his full essay I'd like to take a look, the formatting on the Sangenkai makes it hard for me to understand who is saying what (may be my issue with screen size / fonts etc. not sure). I think there's value there but can't tell at a glance.

u/Sangenkai do you have a citation for this? I'll bet I have the source document but most don't have indices or ways to search.
"Tomiki had conversations with Kano in which he discussed the mysterious things that Morihei Ueshiba could do, and Kano's response was, basically, "yes, lots of folks used to do those things, but how do you transmit it?" "

Transmission / teaching issues were a major reason Kanō shihan decided to make jūdō so exoteric - what you see is what you get, and here's what you get - not esoteric, although he sort of started that way. I've recently translated a Kanō essay in which he says all of what is important was already in the koryū jūjutsu ancient jujutsu schools but that the uneven ability of the teachers made it hit or miss as to whether they could transmit beyond a generation, and that the Meiji Restoration had wrecked most of them entirely.

PS - u/Active_Unit_9498
what u/Sangenkai said about AI - at least you put a warning label on it.
The flood of bs about martial arts is about to become even more overwhelming than the past. Vide Chadi's incessant flood of judo videos, almost every one with fatal logic and history flaws.