The idea that, because Muslims perpetrated 9/11, no Muslims should be allowed to worship near the site. There is already a mosque in Lower Manhattan closer than the so-called ground Zero Mosque, so the entire controversy is asinine regardless. The mosque builders already own the land, and people are free to practice how they like - there's no reason to ban it.
If Muslims wanted to build a monument to all the victims of 9/11 burning in Hell, they have the right to do so. If they wanted to call their mosque the "Terrorist Cathedral" they have the right to do so. Their rights to freedom of speech do not fly out the window because of a sensitive situation.