Re: Where did O-Sensei get his sword training?
Yeah, it's arguing a negative and therefore not much good for supporting any specific point. ("He studied X because there's no evidence he didn't.") But our knowledge is sketchy and these guys were secretive. Under those circumstances "He didn't study X because there's no evidence he did" is also an unsafe claim.
I still want to hear the real story on that menkyo. If it's true, then we are faced with either Takeda giving Ueshiba a menkyo that would make them both a laughingstock, or Takeda and Ueshiba having training we don't know about. The first is a stretch for me; the latter, unsurprising.
No arguments on the subject of Aikido myth-making (or anti-Aikido myth-making, for that matter).