Yeah, thinking more about this. Unchained is really focused on higher wealth people. Typically one factor they would consider is how liquid an asset is. I can see them thinking this would ease the objections of new coiners while still allowing the the security of multisig. 

It sounds like they spent a lot of time designing this. They *might've been* sitting on it until they though the bull market started. It's easier to ride a wave than make one.