These are very good points.
As I see it, there is a slight difference between Deque and GIF:
As far as I can tell, whether one belongs to the "GHIF" or "JIF" camp doesn't indicate much of anything about one's personal background.
People who say "Deck" tend to be the ones who learned it by hearing someone say the word, rather than reading it. To me, this means they probably studied it in a formal Data Structures class, in an English-language college. Sometimes people can be real deques about this -- dismissing or undermining others just because they are self-taught and happen to call the construct "DQ".
(Citation: I first learned about this data structure in a book that called it "kétvégű sor", and I don't think I heard anyone say its English name until well into my professional carrier.)
(Edit: That got a bit darker than I intended. I think the fact that the Deque docs clearly specify the preferred pronunciation used by people in the know is an adequate workaround.)