Libertarians no doubt will wail about the FAA restricting this "important progress". Until they have to shut up because somebody starts delivering thermite bombs to the roofs of buildings with unregistered and unregulated drones. Paid for with bitcoins, of course. :-)
All law enforcement, including laws libertarians like about property and such, is based on making people accountable. When technology produces a new technique for evading accountability, it is proper to require regulation of that technology.