Right, I've got a question since you're a new yorker.
I'm trying to look at the maps here and what I see is this.
Ground Zero is flanked by Three "major" streets it looks like. Barclay on its north, Church on its east, and West St on its West.
It also seems like it's main Subway stop would be "World Trade Center Station".
Now it appears that this proposed Mosque is in a building on the opposite side of the WTC on Barclay, a good 3 blocks from the next major street street (Chambers). Additionally, it appears to me that the "World Trade Center" subway would be the prime subway stop servicing it.
Now, I'll fully admit my only real means of how to view a city is inspired by DC because its the only major metro city I've spent a fair bit of time in. However, in DC, generally the blocks surrouding a Metro Stop that's primarily serviced by said Metro stop are generally viewed as that "area". So the Dupont Circle area is generally considered the multiple blocks within walking distance to the Dupont Circle metro, with that being the closest metro stop for those areas. The China Town section of the city is actually NOT considered just "China Town" but the multiple blocks that would call the China Town metro stop their closest Metro station.
To me, the fact its "2 blocks away" means no more than going into a small town and saying that a store front is "two buildings down" from another. In relation to the city and its size and scope and its infastructure its essentially part of the same generalized area.
I guess the only difference would be is if Cortlandt St Station is considered more the "World Trade Center" station then well, "World Trade Center" station is. If that's the case it would possibly change my view a bit...but as it stands, to me 2 blocks in a large metro city layout still seems like "next door" to me.