The meteor no doubt exploded during day time, as this part of Greenland at this time of the year, late July, experiences light 24/7, thus it may not have been as spectacular as the meteor over Chelyabinsk that fell at dawn. Besides, at 2.1 kilotons it was 200-250 times smaller than the event over Chelyabinsk. The speed of the Greenland meteor was 20 percent higher and exploded at a higher altitude 43 km vs 26 km, than the meteor over Chelyabinsk. In this paper,
http://www.igpp.ucla.edu/public/mkivelso/refs/PUBLICATIONS/Chyba Tunguska.pdf, they claim that higher altitude disintegrations indicate a composition of mainly stone or even carbon. If the Chelyabinsk had a stony composition, so must this one have had. And if the Chelyabinsk meteo was 13,000 tons this one could be of which size? 35-50 tons perhaps.
If this object moved at 24, 4 km per second, it would still take it about 30 minutes from passing the geostationary zone at 36,000 above the Equator, where many communication satellites are placed, before reaching the altitude where it exploded. The spy satellites however are just a few hundred kilometers above the Earth; they had maybe 10 seconds to register. Now, are we to believe that they didn't? Or is it that this meteor only became visible in 3rd Density shortly before explosion, and what if concept of window-fallers is extended to objects like rocks and stones? There seem to be possibilities open that would make standard detection equipment useless, but probably it wasn't. The information from the equipment might have been just classified and it took som red tape to get it out.