Actually, I have no idea how the Dominion's trustworthiness came into it.
A DEM is a way of solving a problem which comes out of nowhere, using previously unknown characters and a large dose of luck.
None of this applied to the end of SoA. The prophets had been clearly established, the fact that the Prophets did it spoke volumes to Sisko's relationship with them (as well as the fact that he was half prophet) and no luck was involved.
So I don't see how it was DeM.