The article says this one was on a pylon (with a spare engine on display on the ground below). Being owned by NASA is important, also being on a military base (the home of USAF test flight!) where it could be removed and easily wheeled into a large-enough hangar without anyone noticing for 5+ months.
Getting any of those planes outside of their museums would be logistically difficult, and of course it would immediately be noticed. And even if you can rent a hangar big enough, and secure it, then you're stuck at BFI/IAD/Wright-Patterson trying to do this impossible task.
Getting any of those planes outside of their museums would be logistically difficult, and of course it would immediately be noticed. And even if you can rent a hangar big enough, and secure it, then you're stuck at BFI/IAD/Wright-Patterson trying to do this impossible task.