Due to the upcoming Zul'Aman changes, the whereabouts of Mojo post-patch were unclear. Thankfully, after some recent PTR testing, it was discovered that the Hex Stick, necessary to "discover" the companion, will continue to drop off of trash mobs even in the heroic five-man version of this dungeon. This is a strong indicator that Mojo will still drop from ZA.
Players should note, however, that a large number of trash groups in Zul'Aman have been removed, possibly making the Hex Sticks a rarer drop. Mobs will also be level 85 elites, making it extremely difficult for players to solo-farm for Mojo.
On the plus side, players are still able to trade the Hex Sticks with other players. Also, unlike before, the item seems to persist through zoning out of the instance. Whether or not this change will occur on live servers and impact the way Hex Sticks can be obtained is yet to be known.