In every city today, the vague excuse of "nuisance" is being used to deprive countless Non-Moslem people of property rights. By extending this concept, you are only underming their rights. Sometimes, you have to protect the rights of people you despise to protect your own. BTW, another pre-9-11 mosque is now just as close to ground zero as this proposed one. Are you suggesting that it also be torn down on this basis?
No, because it is not creating a nuisance. If the presence of a specific building is likely to create a situation where it could pose a safety hazard, then it can be prohibited on the basis that it was going to create a nuisance. For instance if the American Nazi Party or the Aryan Nation Church wanted to build a headquarters next to the Simon Weisenthal Museum, I doubt very seriously if the LA City Council would approve it and secondly I don't think it would be struck down as anything other than a reasonable zoning restriction designed to avoid the creation of a nuisance.
Personally I would favor a law which states that all new buildings built within 800 feet of ground zero must have a 40 foot cross attached to the top in memory of the victims of 9/11.