Lot's of things discussed in chinese arts and DR. You can even learn what he learned from Takeda aiki wise. You can learn from the classics he read. There's lot's of things you can learn about O'Sensei. You can learn from what others said. Thus you wind up with your opinion.
They say the nice thing about science is that it's true whether you believe in it or not....
Similarly, the intellectual thread running from the Chinese arts, through DR, to Ueshiba Sensei is pretty well documented by historians who specialize in such matters. Ignoring that thread won't make it go away.