Seeing as the npc can not judge when a player uses a debuff skill or a stun on the juggernaut, I feel to make it even juggernauts should not be able to select their targets.
This would break the mode even worse than it is now and that is saying something.
To be honest though I can't see anyway of balancing this battle mode to where it is far for both sides. It will either be broken for the juggernaut to the point where the mode goes dead (Most of omega before the NPC adding or the rare case of 2 human opponents showing up) or where the opponents are the majority are the jugs punching bags (When jug first came out through most of delta and the majority of jug fights at this point.)
in fact at this point the only suggestion I can think of that would even help jug out would be if they either
A) Removed the battle mode completely (which was said wasn't happening)
or
B) Remove all human opponents and turn the mode into a NPC 100 of the time with 0 chance of human opponents showing up so 2 vs 2 can have some life once again.