It's one of those things where some corroborating data can help rule it out. But you may be right, we can never be sure. One thing -- didn't the Sagawa dojo have similar stuff posted earlier? If so, maybe Takeda had some core message like this, which the different branches picked up from him.
I was thinking about Takeda-- he saw people do bad things-- from a lot of different angles (per Amdur's HIPS). If his known acts of public violence were indeed during events of unprovoked attack by others against him, maybe he really did develop a vision for a better world. He spent so much time teaching police-- maybe because he saw them as what they ideally are, a way to have society protected from those who make the world bad.
The fact that he had a temper means nothing to me in terms of his vision. In fact both his temper and his proposed vision for a better world may have been fostered by the same experiences of witnessing bad things.
The Sagawa Dojo scroll appears here
It may be that Tokimune Takeda was attempting to capitalize on the popularity of Morihei Ueshiba's Aikido.
On the other hand, if we take Tokimune at face value then it may be that the basic elements of Morihei Ueshiba's thought were already in place rather than being a completely original creation.
There's more of Tokimune's notes on his father's teaching yet to come, with material that points to a much deeper involvement with esoteric Buddhism, especially Shingon, than was previously believed. There are also a series of books published in Japan that argues for that point of view and suggests that there may be some foundation for Tokimune's statement.