According to CNN, the place is already an islamic worship center. Linky.

There is a prayer site in the building currently, so Muslims are peacefully praying in the building already.
So sounds to me like they want to tear down an old building that was converted into a prayer center and make a nice, big, fancier, more proper version of itself. And its father away from ground zero than mosques already in existence. Call me nonplussed.