Because without Google Maps it would have been totally impossible for a member of the public to go to a public location, such as an Opera House, Bazaar or neighbourhood and scope it out for themselves. The absence of Google Maps would have totally scuppered their ability to plan such an attack...
As for Nuclear Installations... those would be totally impossible to know about.
I mean, it's not like there aren't thousands of people employed at those locations, at least some of whom will spill details when plied with alcohol. Not to mention news articles about them, multiple online sources of information like the IAEA, etc where details could be gleaned...
Biting the hand that feeds IT
