Nah man, see here's the thing... YOU keep saying, in a nutshell...
"I don't know anything, I'm trying to learn, but I don't care what the evidence from multiple sources say, I have no reason to disbelieve Frank. Everyone else is just giving "their version" of the history, and it's probably wrong."
So... I say... "if you say so". I don't care if you believe or not. I'm not falling for it, but you can enjoy whatever version of history you wanna believe. If you wanna believe that magic Tengu demons created the art in a dream, or secret chinese monks, or some guy who's movements are very Korean in nature claiming its a Japanese art, or some anonymous teacher on a secret mountain in japan that can never be reached, or that ninja never existed, or any other of the variety of the unvireifed/unverifiable stories I have heard ... thats fine with me. I don't care. I pointed out what the most widely accepted history from numerous sources not all connected said, if you choose to ignore all that more power to you.
Who said I'm ignoring it? I'm still finding it all!