But that's the point of Vizjun.
It was never meant to be a farming uber, the whole point is that the MCS is trying to drown the player in drones to protect itself.
IMO the monsters in there shouldn't have any drops. If the uber really has to have a purpose other than getting the ubercharm, add some extra robot bosses around the map which don't need Purify to be killed but have some other defensive mechanic (eg. one with Jitan-style uberhealing, one that continually spawns minions that shield it, etc.) that have a chance to drop something when you kill them.