zul'jin did nothing wring.
Revendreth is where all souls to be redeemed go - then the individual can choose where they want to go through there. This was deemed by Sire Denathrius and the other 3 covenants where the Arbiter judges and sends a person according to their deeds in life. After redemption a soul can choose to go to the other covenants to serve or become Venthyr and carry out the mission of torturing the prideful and sinful until the cycle begins anew.
Most souls seem to be assigned to random parts of the shadowlands...He did nothing wrong => revendreth; Vashj did 90% only wrong and was a schemer more than a warrior for a large part of her life => maldraxxus; somehow Uther and Alexandros Mograine don't go to the same zone even though they lived by the same principles (Mograine's tragic fate as a DK doesn't make him any less virtuous); Warbrave Oro was a warbrave so...Maldraxxus, maybe ? => nope, Bastion
Anyone found out how to get there? Not getting it with Door of Shadows, keeps saying no path available..
How bitter do you have to be to want to keep your missing eye and arm gone even in the afterlife? Since you can decide what you look like in the afterlife, he chooses to look like that out of spite.
The "they took muh lands!" argument went out the window when the Blood Elves joined the new Horde alongside various Troll tribes. The Amani could've allied with them and shared Quel'thalas with the Blood Elves at that point but he held on to old grudges unlike the elves who moved past them despite having many of their people killed by Trolls over the centuries. Trolls of all types (including the Forest Trolls of Revantusk) now freely walk the lands of Eversong and the streets of Silvermoon after allying with the new Horde that Zul'jin spat on which caused many of his people to be killed as a result. Since he was a Warlord in life he'd fit in great with the Necrolords if he ever manages to move past his hateful grudge.
“We built a mall on your sacred land but it’s okay because we’ll let you come hang out at the mall”