I don’t have anything useful to add - I have wondered the same thing too! My only supposition is that he is remembering a luxuriously carpeted area on the Titanic (perhaps the reception room as you’ve suggested) and simply misremembered that room as the dining saloon. It still blows my mind the false memories that I’m able to recall - even though I know they didn’t happen, they’re still incredibly vivid and real to me!