He wasn't sightseeing. Although I am unsure of whether he was receiving instrument training, or just general type-rating training to get used to his new Cirrus SR-20.
Either way, the instructor was in the plane with him for a reason.
And to Crash.. I know lots about NYC airspace, we studied it extensively in class, seeing that I live and fly only 60nm to the north of it.
The class B airspace surrounding all 3 NY metro airports (KJFK, KLGA, and KEWR) puts severe limits on VFR city flying as it is. There is a VFR corridor that goes down the Hudson, but it is extremely narrow and at some points 500 feet or lower. It's sort of rediculous if you ask me.. the fact that you can fly all the way down the Hudson River at 499 feet, right past the Statue of Liberty, and not once need to legally contact any controller. Sort of hard to picture in a post-9/11 world.. but it's true.
However, I believe the VFR corridor is temprarily closed while this crash is under investigation. But I assure you it will re-open, it always does.