If I'm not mistaken in Koryu there is a culture where you never show someone else your Menkyo scrolls, its personal and private - Not saying Dan is a Menkyo holder or anything, I'm just talking to the etiquette that still exists in some forms of Budo and isn't meant for forum discussion. IMO
I have never heard of that of koryu generally. I could see it being a Daito ryu thing to go along with the factionalism and the inherited pathos of Aizu culture. But whatever, it's private knowledge. So that leads us to here, where we cannot stop wrestling with this material on the internet, but nobody can openly talk about where it comes from.