Airborne to operate as command center in the event of catastrophic event? Maybe needs particular geolocation for reasons of communication ....

I mean, maybe? A Nightwatch is a Command and Control bird though...basically a war room in the sky. If it were only doing data intercept (aka sigint), there are many other birds much better suited to the mission they could put up. Then again, they may have had multiple other aircraft up that were just flying dark, with the Nightwatch flying bright just so a few anons could scratch their chin about what was up. Wouldn't surprise me one bit. Who knows.