Re: Horikawa teaching Shioda?
I think this was, as usual, a great read from Ellis. I think he make a great case for debunking the specific claim that Horikawa sensei taught aiki to Shioda sensei. I did get the sense that Ellis was not advocating that Shioda did not pick something up from Horikawa sensei during this visit, only that the particular event in the photo was not covert instruction of aiki.
My personal belief is that these old relationships were about politics and exposure. I would imagine it would be difficult to start assigning teacher/student relationships within such arrangements, formal or informal. Just seeing some of the material demonstrated may have spurred Shioda sensei to look somewhere where he might not otherwise have looked.