You are still completely missing the point, as if I am arguing about whether they have the "right" or not. The entire problematic regarding this issue is founded in the believe that a recording of a text that has no original performance (no voice actor ever did lines for the text) could possibly be a copyright infringement. If the experience of WoW was fully voiced and the project was recording an alternate version of it then you might have a point.
First, it's optional, it's nowhere available in the game client nor the official site, hence no customer can claim that it's deluding any experience since you specifically would have to install it yourself. Blizzard allows changes to sound files and even re-interpretation of entire sound cues and voice acting all over the place, go ahead and download any addon I would bet 90% are replacing, re-performing or re-designing all kinds of sounds/texts and icons. There is no
logical reason why this is going too far. Changing the sound clues and voice lines of in-game bosses are as much of a redistribution of copyright material as any recorded word by word quest text. (Btw, the answer is none, more on this later)
I don't believe you think this is logical reasonable with the facts presented as it's literally less of a change than most addons that we have out there. Reading out quest text is not a copyright infringement, I could read out the quest text myself and nothing would happen. The creators are not performing any acts publicly, are not charging money for it and I bet a court would not disallow this modification simply because the game is already allowing these kinds of modification and this would be a simple case of double standards. My educated guess would be that Blizzard knows a project like this would be 100% successful and don't want to look bad why they don't record voice lines themselves. So instead of admitting they don't think it's worth it to voice old/all quests they just play the "copyright" card although it's obviously a hypocritically double standard thrown at us giving that (sound) mods like these has been legal for over a decade just in a less ambitious vision.
Regarding:
"Reading the text out-loud or creating software/addon that other people can use that dictates how the creator sees or narrates copyright literature are two different things."
What a whole lot of rubbish, you are telling me no human can simply read out text without dictating his view on the literature? I have no words for this, if that is what you truly believe then we will never have a common ground because that is fundamentally flawed and wrong because it makes any literature worthless by principle if that is what you believe.
Regarding:
"It's redistribution of copyright material, period."
It is not, why? Because that would mean you can listen/read the material WITHOUT the official channel, which is the game/server of WoW. You can't, hence it's not redistributed in any form. Blizzard will still get 100% of revenue whether someone listens to the sound mod or if he doesn't, it would not hold up on court. It is a modification like adding "burp" whenever you click on accept on a quest. It's really as simple as that. What they make it seem like is not what it really is, that's why I am telling you to not just swallow what they feed you.
Elon Musk is right when he proposes laws to be only time limited and then re evaluated over time since governments and corporations alike simply abuse them to do whatever they want. Backwater laws and traditions from 100 years ago surely are fitting, right?
(Not saying this in particular is the case)
Whatever you may answer, have a nice day and hopefully you take something with you and question decisions more often. That's all I can do.