where have you found specific historical reference that Ueshiba specifically studied Chinese martial arts or cosmology?
I don't think Mike is saying that Ueshiba studied under a Chinese instructor to learn these things. I believe he is saying that through-out asia, there is a way of refering to a method of training the body, and that phrases such as 'uniting the ki of heaven and the ki of earth, through the body of man' signify a connection (however diluted or distant) to these methodologies. So you may have these phrases passed down in items like the Kojiki, or other texts, and Ueshiba would have gotten this exposure there.
I believe even in shinto in general, you can see influences from mainland culture and cosmology...but that is really a discussion for the scholars, which I am not.