Personally, I'm not a fan of organized religion, but it helps people cope with their day-to-day lives and sometimes find meaning. As long as the respective leaders don't advocate violence or bilk their customers too much, I don't have a problem with it.
As for this particular mosque, they have a right to build it there as much as anyone, but I would advise them that, in the spirit of sensitivity, they set up shop a few blocks away-- just as, for example, the US should have a right to build an embassy in Nagasaki, but understand that it might not be an advisable or sensitive location and vise versa building a Shaolin temple in Pearl Harbor.
As for TRabinowitz, I'm not sure how much you have traveled in the Middle East (excluding Israel) or even parts of Eurasia and Northern Africa, but I would not characterize radicalized Islam as a marginalized few. Frankly, I understand that you are trying to do an honorable thing and defend one's freedom of religion, but I hope you aren't naive enough to think that this was just the unfortunate manifestation of a radicalized few. Poverty, illiteracy, a floundering sense of identity, and unfortunately violent religious propaganda have galvanized quite a few young men, particularly in Yemen.
A few books that you might be interested in are The Looming Tower by Lawrence Wright, Jawbreaker by Gary Berntsen, Ghost Wars by Steve Coll, or The Shia Revival by Vali Nasr.