intellegent,
Why do you assume that everyone is ashkenazi? Do you think the Rambam pronounced it “kesuba”?
Most ashkenazim I know in Israel, use the Israeli (sephardi) pronounciation for conversation and switch to ashkenazi pronounciation for tefilla.
I can’t see why you have your knickers in a twist over someone using the sephardi havara for a comment on the YWN coffee room.
By the way, when you say “shabbos” do you put the accent on the first syllable or the second? One is correct and one is incorrect regardless of whether you are ashkenazi or sephardi.