This is sort of the issue with making Zovaal the big overarching hand behind it all, as well. Because it gives some sliver of agency removal to Arthas, which in my opinion not only cheapens him as a villain but sends an extremely weird and uncomfortable message regarding what he did to Sylvanas and tens of thousands of others at a time when the current narrative is already really weird when we take into account the lawsuit.
The original story was an excellent subversion of what were at the time classic fantasy tropes. Arthas was the handsome prince, the nascent hero, and his own actions led him to choose power over his soul, with the claim of it being to ‘save his people’, even though at that point it was more about himself and his own selfish desires.
Scourge level undeath is the most horrific thing you can inflict on someone in the WoW canon, in my opinion. And what he did to Sylvanas has always been very much stressed as very bad. Profane rituals, violations of body and soul, then months spent as his minion, watching and helping him commit atrocities all while her own mind was still intact.
Making it the Jailer’s fault would be uh… bad.
If he’s meant to be in Revendreth then toss him in there but they shouldn’t make him a victim.