It's already restricted, don't think you have to worry about overall length. Same classification as a pistol.
I don't really see any point since you can't fire it folded and both my Swiss (sold) and HK fold and can be fired folded and I never fold them, you can't hit anything with them folded. Transport makes no difference to me since I just put them in a case big enough or throw them on the seat of the truck since they are non restricted. The motorcycle carry is about the only thing I can see it being handy for but an AR still needs to be locked into something and as has already been said it's smaller, easier, and cheaper to push 2 pins.
If you had an AR with a recoil system that didn't use the buffer it would make more sense but I can only think of one piston rifle design that has a recoil system that would work (ZM).
Be sure to post lots of pics if you get one as it looks cool but for me it isn't worth the money.