What a strange comment. Of course they can hear everything. That's what it's there for.....
Well, it was my first time flying UA
so it was my first time to experience Channel 9. After this comment was made, I didn't hear anything else on Ch. 9 so I asked the F/A about it. She said that there was a malfunction.
I know Ch. 9 is supposed to let you listen to ATC, but I'm not sure that it's supposed to be able to let you listen to interphone conversations between the cabin crew and cockpit, for obviously understandable reasons. I'm guessing that was the "malfunction".
Last year 1,944 New Yorkers saw something and said something.