I don't think they'd make a direct parallel with the story of Jesus, I am pretty sure that would not go down well at all...I certainly wouldn't like it.
I take it the parallels with the last supper are because its a long table, inquisitor in the middle and six followers either side? It would be a bit obvious/clumsy of them if that had such a direct parallel of meaning. Also, much of the importance of the Last Supper is what the disciples are doing in the painting, Judas is set apart from them. In the inquisition picture they are all disconnected and not interacting, a few of them seem to be looking at the Inquisitor and Solas is one of them, so if anything he appears more engaged.
I hope that if there is any thematic comparison between the inquisition picture and the last supper that it is perhaps just introducing the idea that the inquisitor could be betrayed, and that they could be betrayed by any one of them.
I also doubt that not yet being revealed would have anything to do with him being a Judas character. If anything I think they are holding back on Dorian, Solas and Scribbles because they want to save some of the new characters. It would seem logical that Solas or Dorian are likely to be next as we do know something about them, with scribbles being the last.
My biggest fear for DAI is that the fate of companions is set in stone, being able to alter outcomes for companions is crucial to my enjoyment of Bioware games.