is the nut captured? I like the idea, but having to deal with loose parts while also dealing with a flat is not something I want to subject myself to.
Quick answer is no. The nut is held in place to *some* extent with a flat-faced (matches the flat faces on the nut) incut section of the NDS dropout. But it won't just stay there when you remove the axle. So reinstalling the wheel is definitely a 2-hand job, a bit harder than on a QR15 suspension fork.
You could braze in your own nut pretty easily, though, if you wanted to.