Even if:The owners, financial backers, builders, imams, members, and patrons of the mosque are completely innocent of anything and everything you could think of, and they have complete legal rights of property ownership to build a religious facility.
You cannot deny;
That the fanatic, hard-line, Islamic terrorists around the world and those that support them will view the 13 story mosque overlooking the WTC neighborhood as a symbolic monument of triumph and victory. That these same groups, who wish the US and its citizens harm, will celebrate its construction and be emboldened, encouraged, and aided in their propaganda to continue their terrorist jihad against the US and western civilization.
Now . . .
It is the primary purpose and duty of the United States government to protect its citizens. Does that not include deterring and prohibiting aide to those that have sworn to do us harm?