Kyrestia the Firstborne calls him "that monster"
others say that he was in defiance of the first ones so the eternal ones bound together and imprisoned him in the Maw, forever to be its Jailer.
Primus says he betrayed them.
Eventually we (i assume) will get to some point in this expansion where it will be revealed why he was imprisoned.
At which point what would make you second guess him imprisonment? Isnt it curious that the default mode of operation for Oribos is to funnel everything into the Maw? I mean if not for the Arbiter everything gets sent to hell. Why though? Seems like bad design to just automatically send everyone to hell if no Arbiter present or perhaps...is it the normal and another system was put into place to override it?
Imagine such that the Jailer was the initial ruler of the underworld as assigned by the First Ones. He did the Arbiters job but not so methodically as the 4 realms, Bastion, Ardenweald, Revendreth and Maldraxxus. But instead, the Maw as it is right now was the major landmass but divided into categories or layers w.e. However when the First Ones told him to overhaul that system placing him as the ruler of hell, while creating other realms for his brothers and sisters [the eternal ones] to govern those areas he got pissed and lashed out.
As a result his land was shattered and in its broken pieces. And Zovaal jailed within it, forced to serve a purpose, much like Argus was carved out of his planet and forced to regenerate the burning legion.
Would this make you side with him?
Or would you prefer the older version which is:
Kyrians (must be, thanks Devos! you idiot!) non judgemental in their ferrying of souls but for that they must let go of their memories otherwise they cant carry it out fairly.
Maldraxxus is singular in its purpose, to defend the shadowlands from attack
Ardenweald works to send back souls that are greater than the average joe, employing normal souls carrying out this task
Revendreth to offer souls a second chance, who upon succeeding either join them or go to one of the previous 3 realms.
Or finally, fall into the maw having failed their chance at redemption.