Dear Youdont,
This post of yours is what confuses me.
YOU ““Rav Moshe disagreed regarding their halachic concerns, because there were city’s that established eruvin whose population was greater than 600,000 (but he had his own reason to oppose).””
ME “And therefore? Rav Moshe’s teshuvos lay out his reasoning. I don’t know what is missing here.”
YOU I am referring to the fact that these gedolim on the Manhattan kk could not have opposed the eruv for the same reason as Rav Moshe. His opposition was almost exclusive to Manhattan (and later on Brooklyn). However, the others signors seemed to be opposing any eruv in a city containing shishim ribo. Or according to Rav Aharon all city eruvin past a present.
End of your post, Now me again.
So I am left very befuddled how you just do away Rav Moshe with a claim of misinformation. (Which nobody managed to get Reb Dovid to recant.) Rav Moshe goes through all the reasons why Manhattan as a reshus harrabim would be problematic. He offers alternatives why it could be permitted. His result is not to rely on these permissions. And that leaves us – very clearly – that Rav Moshe held the eiruv is not good enough. You can disagree with Rav Moshe. But what do you mean that it is permitted according to Rav Moshe, when he himself concluded not to use these permissions?
Are you claiming that Rav Moshe does not agree with his own interpretation of reshus harrabim according to the SA? Because the entire teshuva is a straight line. Nowhere does Rav Moshe write that we should count the exact population.
Just because Rav Moshe disagreed with the machmirim, it doesn’t mean that he disagreed with Rav Moshe.
Other than the misinformation claim, which I think is the wrong way to read Rav Moshe’s teshuvos – there doesn’t seem to be any way to claim that Rav Moshe permitted an eiruv in Brooklyn.