I often here people quoting gedolim and have learned NOT to believe the quotes [or stories for that matter] so quickly.
Cases in point: I have often heard the story of how Rav Moshe Feinstein was at a separate seating wedding and complained that he wants to sit next to his Rebbetzin.
Hmmmmm.
Anyway - in the recently published Mesores Moshe written by Rav Moshe's grandson, he is quoted as saying that mixed seating at smachos is American nonsense [see there for the exact quote - I don't have it in front of me]. He was clearly not a proponent. Rav Moshe could sit next to his Rebbetzin at home if he so desired. I must note that in his Igros Moshe he explicitly permits mixed seating. There is, however, a big difference between being permitted and being the ideal. This is borne out by the Levush who famously writes: "They said in Sefer Chassidim that wherever men and women see each other, such as at a wedding meal, one should not say "shehasimcha bim'ono" in the blessing as there is no simchah before Hashem where there are licentious thoughts. But nowadays [people] are not careful about this, and perhaps the reason is that nowadays it is very common to have women amongst the men, and there are not as many indecent thoughts..." Some would say that they don't believe Rav Moshe's grandson and he really WAS in favor of mixed seating. Maybe. Maybe not. But I am very skeptical... [PS - I would also question the assertion of the Levush that today people have fewer indecent thoughts].
I fished around a little and found this letter to the editor from the Jewish Press: From what I was told, two of the four weddings Reb Moshe made had completely separate seating. At Reb Reuven’s wedding, there were some mixed tables to accommodate those from his wife’s side who wouldn’t sit any other way. Reb Reuven has acknowledged making the same accommodation for mechutonim at several of his children’s weddings. At Rav Tendler’s wedding, I was told, the Feinstein side sat separately while the Tendler side sat mixed.
Permitted but not ideal.
Case 2: I recently read that Rav Moshe said that one should say Hallel on Yom Ha-atzmaut. Interesting:). Humor, I am told, is one of my strong points. This makes me positively giddy. OF COURSE I can't prove that he DIDN'T say it but I also can't prove that he didn't say that monkeys are great violinists. It just doesn't seem probable. There is obviously no record of this in his Igros Moshe
If he DID believe this to be the halacha then it would make sense that they said Hallel in his Yeshiva which I am 99.9 percent certain that they did not. Many of his students are still alive and this can be verified.
If someone WANTS to say Hallel they can read through Professor Rakover's book on the topic [as did I in my youthful journeys through the stacks of the legendary library of Yeshivat HaKotel] and find halachic justification. But please, not Rav Moshe.
Case 3: A well known Rabbi and lecturer quoted the Lubavitcher Rebbe as saying in a letter that one may take an entrance exam for medical school on Shabbos. He just neglected to cite a source. Because there is none:).
This same character quoted numerous gedolim as being very lenient about woman's hair covering. It was later discovered that it was a big hoax and almost certainly was the figment of his fertile imagination. [I neglect to link you to where this scandalous story is covered because I have no interest in bashing individuals - even liars - but in conveying lessons about life].
So before you believe someone, verify the source and rationale. My favorite book does this on every page. It is called "Gemara".
:)