That would be difficult, since Tadashi Abe didn't even begin Aikido until 1942.
Ueshiba did think enough of Mochizuki that he wanted to adopt him into the family and make him his successor. In 1951 he taught Aikido in Europe with Ueshiba's blessing. His 10th dan was specifically approved by Kisshomaru Ueshiba in 1979.
Still makes sense. He says that meeting was just after the war so must be around 1945.
What it's got to do with the o/p I don't know.
That particular time however was not Aikido, it was Aiki jujutsu. As to how spiritual that particular incident was I suppose depends on the charachters involved and the point being made.