Well obviously this is something of a marketing gimmick. I suppose one could think of them as "dealer only" service manuals in the sense that "only dealers" typically have them. But in the sense of it being some kind of confidential material that is only available to authorized dealers, that is false.
I would also like to add that until all dealer and auto repair shop orders have been filled, the manufacturer may in fact restrict sales to the public. Dealers and repair shops get first crack at the supply.