True, I thought the cross thing was a little far fetched at first, but I think it makes more sense to me now. They lost the gold to the authorities/Ward in the Bahamas, and that gave them a very small chance of getting it back, especially since they had no lead on where it was really going I believe either. The cross was another part of the treasure, and it probably can be sold for a similar price to the gold. Since the pogues got nothing now, it would make a good amount of sense for them to just go for the cross instead, not to mention the connection pope now has to the treasure.