1 minute ago, Drasnighta said:This exactly.
"Exception that proves the rule" - it doesn't even make sense in a universe where everything is connected in the Force, and Force ghosts are a thing. (And one-offs hardly prove anything - Col Tigh exclaimed "Jesus Christ" in the new Battlestar Galactica, a character that flatly does not exist in that setting. "Lords of Kobol" would have made more sense in context, but actors gonna be actors and make those kind of mistakes...)
This reference in Star Wars is simply extremely uncommon , likely because (as noted), it doesn't fit with the mythology of the universe at all.