I have been trying to get my mind around how that Maul pack warrants a spot in the Build-Up assortment with the 2-packs, and the only rationalization I can come to is that the 2 packs didn't cost out as cheap as they had initially planned, so a single figure pack is there to balance out the whole assortment. And Maul in an alternate costume was was determined to be enough of a draw.
I would be interested to know if he was intended to be half of a 2 pack originally, and who the other half might have been planned as?