It caught my attention because of the non-standard wording. Normally the regulations say that test flights should be over sparsely populated areas and/or avoid densely populated areas.
I'm afraid that to say "specific airspace over unpopulated areas" and have that odd phrase repeated in hundreds of news stories around the world will make it just that much harder for people to have confidence not only in he 787 but in the FAA who certified it.
(The only other references I could find about requiring tests over unpopulated areas were for unmanned drones and space vehicles.)