I think this is another way aikido related to weapon because if we assume easy access to a weapon, then attacks are much more committed and there is less jockeying for position as it gives time to access and deploy the weapon.
A testable hypohesis -- give each person a tanto or bokken in their belt (the latter might be sort of cumbersome for safety, but...) and then put them at arms length. See whether or not aikido training is helpful. (I can think of a few possible techniques...like if you're cross-wrist-grabbed while grabbing a katana, you can apply nikyo with your hand or the tsuka.)
It still seems like the methods should be -usable- in regular unarmed grappling, even if they aren't optimal. I dunno.
I recall seeing this sort of thing demonstrated at at Friendship Demo or something. Not the aliveness part, but the "Aikido waza as ways to get a sword out". Wasn't Shoji Nishio-sensei interested in this aspect of aikido?