youdontsay,
I found an old post of yours which states:
“You see an oral explanation cannot be in direct contradiction to a written teshuvah. The fact is Rav Moshe maintained that an eruv cannot be erected in any part of an area of 12 mil by 12 mil containing a population of approximately 3 million. Therefore, it is irrelevant (based on Rav Moshe’s teshuvos) if an area encompassing such a population consisted of individual neighborhoods, since an eruv cannot be erected in any part of this area. Sorry, Rav Moshe could not have made such a distinction.”
Now, when you say that one can make in a subsection of Brooklyn, does that mean A) even when Brooklyn would meet the 12×12 mil criterion, or B) only when it would not (which you state it doesn’t – just like KGH doesn’t). If you’ll say A) then you’re contradicting what you wrote in the old post I referenced.