What is being disputed is whether it is right for them to do so. Whether they ought to build such a structure so near that particular site.
This raises 2 questions.
1. If you are only arguing whether it is right for them to do it, then it is nothing but an intellectual exercise with no meaning to it since those arguing have no say in the matter.
2. If you are arguing that they shouldn't do it and your say should carry some weight, then it does intrude into their constitutional right to do it.
I am curious as to whether you think those arguing against it should have some say in whether it is built or not.
Arguing whether they ought to do it is not only an intellectual exercise, because if, for example, Consolidated Edison which owns a part of the site decides it would be wrong its property to the Muslim group, the building will not be erected on that site, and arguing whether the structure ought not to be built may persuade them not to sell the property.
If (for example) my arguing that it is wrong for people ignorant of how our government works to vote even thought they have the right to vote, does not "intrude" on their constitutional right to vote, then how would my arguing that even if the Muslim group has the right to build, that it would be wrong for them to build "intrude" on their Constitutional rights? Perhaps the central point I was making is that even if there is the right to do something it might still be wrong for someone to exercise
that right. For instance, even if I have the right to vote, if I am voting for someone because I am being bribed to do so, and not because I think he is best for the job, it would be wrong for me to vote for him even though I have the right to do so, for it would be wrong for me to vote because I took a bribe. Don't you agree? Isn't there a big difference between having the right to do X, and whether X is the (morally) right thing for me to do (whether I should exercise that right)?
I don't know what you mean by "having a say". If you mean "have the power to permit or disallow the erection of the building" my answer is no unless they are give that power. But if you mean should be able to express their views about the matter, then of course they should "have a say". In a democracy, citizen always have not only the right to express their views, but in most circumstance should be allowed to exercise
that right. Your very question here raises the difference between (1) having a right, and (2) its being right for someone to exercise the right. And that was the distinction my post was based on.